diff --git a/plugins/kolab_files/lib/kolab_files_engine.php b/plugins/kolab_files/lib/kolab_files_engine.php
index 52b706be..d464f9e8 100644
--- a/plugins/kolab_files/lib/kolab_files_engine.php
+++ b/plugins/kolab_files/lib/kolab_files_engine.php
@@ -1,1808 +1,1809 @@
 <?php
 
 /**
  * Kolab files storage engine
  *
  * @version @package_version@
  * @author Aleksander Machniak <machniak@kolabsys.com>
  *
  * Copyright (C) 2013-2015, Kolab Systems AG <contact@kolabsys.com>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
  * published by the Free Software Foundation, either version 3 of the
  * License, or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU Affero General Public License for more details.
  *
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
 class kolab_files_engine
 {
     private $plugin;
     private $rc;
     private $url;
     private $url_srv;
+    private $filetypes_style;
     private $timeout = 600;
     private $files_sort_cols    = array('name', 'mtime', 'size');
     private $sessions_sort_cols = array('name');
 
     const API_VERSION = 4;
 
 
     /**
      * Class constructor
      */
     public function __construct($plugin, $client_url, $server_url = null)
     {
         $this->url     = rtrim(rcube_utils::resolve_url($client_url), '/ ');
         $this->url_srv = $server_url ? rtrim(rcube_utils::resolve_url($server_url), '/ ') : $this->url;
         $this->plugin  = $plugin;
         $this->rc      = $plugin->rc;
         $this->timeout = $this->rc->config->get('session_lifetime') * 60;
     }
 
     /**
      * User interface initialization
      */
     public function ui()
     {
         $this->plugin->add_texts('localization/');
 
         $templates = array();
 
         // set templates of Files UI and widgets
         if ($this->rc->task == 'mail') {
             if (in_array($this->rc->action, array('', 'show', 'compose'))) {
                 $templates[] = 'compose_plugin';
             }
             if (in_array($this->rc->action, array('show', 'preview', 'get'))) {
                 $templates[] = 'message_plugin';
 
                 if ($this->rc->action == 'get') {
                     // add "Save as" button into attachment toolbar
                     $this->plugin->add_button(array(
                         'id'         => 'saveas',
                         'name'       => 'saveas',
                         'type'       => 'link',
                         'onclick'    => 'kolab_directory_selector_dialog()',
                         'class'      => 'button buttonPas saveas',
                         'classact'   => 'button saveas',
                         'label'      => 'kolab_files.save',
                         'title'      => 'kolab_files.saveto',
                         ), 'toolbar');
                 }
                 else {
                     // add "Save as" button into attachment menu
                     $this->plugin->add_button(array(
                         'id'         => 'attachmenusaveas',
                         'name'       => 'attachmenusaveas',
                         'type'       => 'link',
                         'wrapper'    => 'li',
                         'onclick'    => 'return false',
                         'class'      => 'icon active saveas',
                         'classact'   => 'icon active saveas',
                         'innerclass' => 'icon active saveas',
                         'label'      => 'kolab_files.saveto',
                         ), 'attachmentmenu');
                 }
             }
 
             $list_widget = true;
         }
         else if (!$this->rc->action && in_array($this->rc->task, array('calendar', 'tasks'))) {
             $list_widget = true;
             $templates[] = 'compose_plugin';
         }
         else if ($this->rc->task == 'files') {
             $templates[] = 'files';
 
             // get list of external sources
             $this->get_external_storage_drivers();
 
             // these labels may be needed even if fetching ext sources failed
             $this->plugin->add_label('folderauthtitle', 'authenticating', 'foldershare', 'saving');
         }
 
         if ($list_widget) {
             $this->folder_list_env();
 
             $this->plugin->add_label('save', 'cancel', 'saveto',
                 'saveall', 'fromcloud', 'attachsel', 'selectfiles', 'attaching',
                 'collection_audio', 'collection_video', 'collection_image', 'collection_document',
                 'folderauthtitle', 'authenticating'
             );
         }
 
         // add taskbar button
         if (empty($_REQUEST['framed'])) {
             $this->plugin->add_button(array(
                 'command'    => 'files',
                 'class'      => 'button-files',
                 'classsel'   => 'button-files button-selected',
                 'innerclass' => 'button-inner',
                 'label'      => 'kolab_files.files',
                 'type'       => 'link'
                 ), 'taskbar');
         }
 
         $caps = $this->capabilities();
 
         $this->plugin->include_stylesheet($this->plugin->local_skin_path().'/style.css');
         $this->plugin->include_script($this->url . '/js/files_api.js');
         $this->plugin->include_script('kolab_files.js');
 
         $this->rc->output->set_env('files_url', $this->url . '/api/');
         $this->rc->output->set_env('files_token', $this->get_api_token());
         $this->rc->output->set_env('files_caps', $caps);
         $this->rc->output->set_env('files_api_version', $caps['VERSION'] ?: 3);
         $this->rc->output->set_env('files_user', $this->rc->get_user_name());
 
-        if ($caps['DOCEDIT']) {
+        if ($caps['DOCEDIT'] ?? false) {
             $this->plugin->add_label('declinednotice', 'invitednotice', 'acceptedownernotice',
                 'declinedownernotice', 'requestednotice', 'acceptednotice', 'declinednotice',
                 'more', 'accept', 'decline', 'join', 'status', 'when', 'file', 'comment',
                 'statusaccepted', 'statusinvited', 'statusdeclined', 'statusrequested',
                 'invitationaccepting', 'invitationdeclining', 'invitationrequesting',
                 'close', 'invitationtitle', 'sessions', 'saving');
         }
 
         if (!empty($templates)) {
             $collapsed_folders = (string) $this->rc->config->get('kolab_files_collapsed_folders');
 
             $this->rc->output->include_script('treelist.js');
             $this->rc->output->set_env('kolab_files_collapsed_folders', $collapsed_folders);
 
             // register template objects for dialogs (and main interface)
             $this->rc->output->add_handlers(array(
                 'folder-create-form' => array($this, 'folder_create_form'),
                 'folder-edit-form'   => array($this, 'folder_edit_form'),
                 'folder-mount-form'  => array($this, 'folder_mount_form'),
                 'folder-auth-options'=> array($this, 'folder_auth_options'),
                 'file-search-form'   => array($this, 'file_search_form'),
                 'file-rename-form'   => array($this, 'file_rename_form'),
                 'file-create-form'   => array($this, 'file_create_form'),
                 'file-edit-dialog'   => array($this, 'file_edit_dialog'),
                 'file-session-dialog' => array($this, 'file_session_dialog'),
                 'filelist'           => array($this, 'file_list'),
                 'sessionslist'       => array($this, 'sessions_list'),
                 'filequotadisplay'   => array($this, 'quota_display'),
                 'document-editors-dialog' => array($this, 'document_editors_dialog'),
             ));
 
             if ($this->rc->task != 'files') {
                 // add dialog(s) content at the end of page body
                 foreach ($templates as $template) {
                     $this->rc->output->add_footer(
                         $this->rc->output->parse('kolab_files.' . $template, false, false));
                 }
             }
         }
     }
 
     /**
      * Engine actions handler
      */
     public function actions()
     {
         if ($this->rc->task == 'files' && $this->rc->action) {
             $action = $this->rc->action;
         }
         else if ($this->rc->task != 'files' && $_POST['act']) {
             $action = $_POST['act'];
         }
         else {
             $action = 'index';
         }
 
         $method = 'action_' . str_replace('-', '_', $action);
 
         if (method_exists($this, $method)) {
             $this->plugin->add_texts('localization/');
             $this->{$method}();
         }
     }
 
     /**
      * Template object for folder creation form
      */
     public function folder_create_form($attrib)
     {
         $attrib['name'] = 'folder-create-form';
         if (empty($attrib['id'])) {
             $attrib['id'] = 'folder-create-form';
         }
 
         $input_name    = new html_inputfield(array('id' => 'folder-name', 'name' => 'name', 'size' => 30));
         $select_parent = new html_select(array('id' => 'folder-parent', 'name' => 'parent'));
         $table         = new html_table(array('cols' => 2, 'class' => 'propform'));
 
         $table->add('title', html::label('folder-name', rcube::Q($this->plugin->gettext('foldername'))));
         $table->add(null, $input_name->show());
         $table->add('title', html::label('folder-parent', rcube::Q($this->plugin->gettext('folderinside'))));
         $table->add(null, $select_parent->show());
 
         $out = $table->show();
 
         // add form tag around text field
         if (empty($attrib['form'])) {
             $out = $this->rc->output->form_tag($attrib, $out);
         }
 
         $this->plugin->add_label('foldercreating', 'foldercreatenotice', 'create', 'foldercreate', 'cancel', 'addfolder');
         $this->rc->output->add_gui_object('folder-create-form', $attrib['id']);
 
         return $out;
     }
 
     /**
      * Template object for folder editing form
      */
     public function folder_edit_form($attrib)
     {
         $attrib['name'] = 'folder-edit-form';
         if (empty($attrib['id'])) {
             $attrib['id'] = 'folder-edit-form';
         }
 
         $input_name    = new html_inputfield(array('id' => 'folder-edit-name', 'name' => 'name', 'size' => 30));
         $select_parent = new html_select(array('id' => 'folder-edit-parent', 'name' => 'parent'));
         $table         = new html_table(array('cols' => 2, 'class' => 'propform'));
 
         $table->add('title', html::label('folder-edit-name', rcube::Q($this->plugin->gettext('foldername'))));
         $table->add(null, $input_name->show());
         $table->add('title', html::label('folder-edit-parent', rcube::Q($this->plugin->gettext('folderinside'))));
         $table->add(null, $select_parent->show());
 
         $out = $table->show();
 
         // add form tag around text field
         if (empty($attrib['form'])) {
             $out = $this->rc->output->form_tag($attrib, $out);
         }
 
         $this->plugin->add_label('folderupdating', 'folderupdatenotice', 'save', 'folderedit', 'cancel');
         $this->rc->output->add_gui_object('folder-edit-form', $attrib['id']);
 
         return $out;
     }
 
     /**
      * Template object for folder mounting form
      */
     public function folder_mount_form($attrib)
     {
         $sources = $this->rc->output->get_env('external_sources');
 
         if (empty($sources) || !is_array($sources)) {
             return '';
         }
 
         $attrib['name'] = 'folder-mount-form';
         if (empty($attrib['id'])) {
             $attrib['id'] = 'folder-mount-form';
         }
 
         // build form content
         $table        = new html_table(array('cols' => 2, 'class' => 'propform'));
         $input_name   = new html_inputfield(array('id' => 'folder-mount-name', 'name' => 'name', 'size' => 30));
         $input_driver = new html_radiobutton(array('name' => 'driver', 'size' => 30));
 
         $table->add('title', html::label('folder-mount-name', rcube::Q($this->plugin->gettext('name'))));
         $table->add(null, $input_name->show());
 
         foreach ($sources as $key => $source) {
             $id    = 'source-' . $key;
             $form  = new html_table(array('cols' => 2, 'class' => 'propform driverform'));
 
             foreach ((array) $source['form'] as $idx => $label) {
                 $iid = $id . '-' . $idx;
                 $type  = stripos($idx, 'pass') !== false ? 'html_passwordfield' : 'html_inputfield';
                 $input = new $type(array('size' => 30));
 
                 $form->add('title', html::label($iid, rcube::Q($label)));
                 $form->add(null, $input->show('', array(
                         'id'   => $iid,
                         'name' => $key . '[' . $idx . ']'
                 )));
             }
 
             $row = $input_driver->show(null, array('value' => $key))
                 . html::img(array('src' => $source['image'], 'alt' => $key, 'title' => $source['name']))
                 . html::div(null, html::span('name', rcube::Q($source['name']))
                     . html::br()
                     . html::span('description hint', rcube::Q($source['description']))
                     . $form->show()
                 );
 
             $table->add(array('id' => $id, 'colspan' => 2, 'class' => 'source'), $row);
         }
 
         $out = $table->show() . $this->folder_auth_options(array('suffix' => '-form'));
 
         // add form tag around text field
         if (empty($attrib['form'])) {
             $out = $this->rc->output->form_tag($attrib, $out);
         }
 
         $this->plugin->add_label('foldermounting', 'foldermountnotice', 'foldermount',
             'save', 'cancel', 'folderauthtitle', 'authenticating'
         );
         $this->rc->output->add_gui_object('folder-mount-form', $attrib['id']);
 
         return $out;
     }
 
     /**
      * Template object for folder authentication options
      */
     public function folder_auth_options($attrib)
     {
         $checkbox = new html_checkbox(array(
             'name'  => 'store_passwords',
             'value' => '1',
             'class' => 'pretty-checkbox',
         ));
 
         return html::div('auth-options',
             html::label(null, $checkbox->show() . ' ' . $this->plugin->gettext('storepasswords'))
             . html::p('description hint', $this->plugin->gettext('storepasswordsdesc'))
         );
     }
 
     /**
      * Template object for sharing form
      */
     public function folder_share_form($attrib)
     {
         $folder = rcube_utils::get_input_value('_folder', rcube_utils::INPUT_GET, true);
 
         $info = $this->get_share_info($folder);
 
         if (empty($info) || empty($info['form'])) {
             $msg = $this->plugin->gettext($info === false ? 'sharepermissionerror' : 'sharestorageerror');
             return html::div(array('class' => 'boxerror', 'id' => 'share-notice'), rcube::Q($msg));
         }
 
         if (empty($attrib['id'])) {
             $attrib['id'] = 'foldershareform';
         }
 
         $out = '';
 
         foreach ($info['form'] as $mode => $tab) {
             $table  = new html_table(array(
                     'cols'        => ($tab['list_column'] ? 1 : count($tab['form'])) + 1,
                     'data-mode'   => $mode,
                     'data-single' => $tab['single'] ? 1 : 0,
             ));
             $submit = new html_button(array('class' => 'btn btn-secondary submit'));
             $delete = new html_button(array('class' => 'btn btn-secondary btn-danger delete'));
             $fields = array();
 
             // Table header
             if (!empty($tab['list_column'])) {
                 $table->add_header(null, rcube::Q($tab['list_column_label']));
             }
             else {
                 foreach ($tab['form'] as $field) {
                     $table->add_header(null, rcube::Q($field['title']));
                 }
             }
             $table->add_header(null, '');
 
             // Submit form
             $record = '';
             foreach ($tab['form'] as $index => $field) {
                 $add = '';
                 if ($field['type'] == 'select') {
                     $ff = new html_select(array('name' => $index));
                     foreach ($field['options'] as $opt_idx => $opt) {
                         $ff->add($opt, $opt_idx);
                     }
                 }
                 else if ($field['type'] == 'password') {
                     $ff = new html_passwordfield(array(
                             'name'        => $index,
                             'placeholder' => $this->rc->gettext('password'),
                     ));
                     $add = new html_passwordfield(array(
                             'name'        => $index . 'confirm',
                             'placeholder' => $this->plugin->gettext('confirmpassword'),
                     ));
                     $add = $add->show();
                 }
                 else {
                     $ff = new html_inputfield(array(
                             'name'              => $index,
                             'data-autocomplete' => $field['autocomplete'],
                             'placeholder'       => $field['placeholder'],
                     ));
                 }
 
                 if (!empty($tab['list_column'])) {
                     $record .= $ff->show() . $add;
                 }
                 else {
                     $table->add(null, $ff->show() . $add);
                 }
                 $fields[$index] = $ff;
             }
 
             if (!empty($tab['list_column'])) {
                 $table->add('form', $record);
             }
 
             $hidden = '';
             foreach ((array) $tab['extra_fields'] as $key => $default) {
                 $h = new html_hiddenfield(array('name' => $key, 'value' => $default));
                 $hidden .= $h->show();
             }
 
             $table->add(null, $hidden . $submit->show(rcube::Q($tab['label'] ?: $this->plugin->gettext('submit'))));
 
             // Existing entries
             foreach ((array) $info['rights'] as $entry) {
                 if ($entry['mode'] == $mode) {
                     if (!empty($tab['list_column'])) {
                         $table->add(null, html::span(array('title' => $entry['title'], 'class' => 'name'), rcube::Q($entry[$tab['list_column']])));
                     }
                     else {
                         foreach ($tab['form'] as $index => $field) {
                             if ($fields[$index] instanceof html_select) {
                                 $table->add(null, $fields[$index]->show($entry[$index]));
                             }
                             else if ($fields[$index] instanceof html_inputfield) {
                                 $table->add(null, html::span(array('title' => $entry['title'], 'class' => 'name'), rcube::Q($entry[$index])));
                             }
                         }
                     }
 
                     $hidden = '';
                     foreach ((array) $tab['extra_fields'] as $key => $default) {
                         if (isset($entry[$key])) {
                             $h = new html_hiddenfield(array('name' => $key, 'value' => $entry[$key]));
                             $hidden .= $h->show();
                         }
                     }
 
                     $table->add(null, $hidden . $delete->show(rcube::Q($this->rc->gettext('delete'))));
                 }
             }
 
             $this->rc->output->add_label('kolab_files.updatingfolder' . $mode);
 
             $out .= html::tag('fieldset', $mode, html::tag('legend', null, rcube::Q($tab['title'])) . $table->show()) . "\n";
         }
 
         $this->rc->autocomplete_init();
 
         $this->rc->output->set_env('folder', $folder);
         $this->rc->output->set_env('form_info', $info['form']);
         $this->rc->output->add_gui_object('shareform', $attrib['id']);
         $this->rc->output->add_label('kolab_files.submit', 'kolab_files.passwordconflict', 'delete');
 
         return html::div($attrib, $out);
     }
 
     /**
      * Template object for file edit dialog/warnings
      */
     public function file_edit_dialog($attrib)
     {
         $this->plugin->add_label('select', 'create', 'cancel', 'editfiledialog', 'editfilesessions',
             'newsession', 'ownedsession', 'invitedsession', 'joinsession', 'editfilero', 'editfilerotitle',
             'newsessionro'
         );
 
         return '<div></div>';
     }
 
     /**
      * Template object for file session dialog
      */
     public function file_session_dialog($attrib)
     {
         $this->plugin->add_label('join', 'open', 'close', 'request', 'cancel',
             'sessiondialog', 'sessiondialogcontent');
 
         return '<div></div>';
     }
 
     /**
      * Template object for dcument editors dialog
      */
     public function document_editors_dialog($attrib)
     {
         $table = new html_table($attrib + array('cols' => 3, 'border' => 0, 'cellpadding' => 0));
 
         $table->add_header('username', $this->plugin->gettext('participant'));
         $table->add_header('status', $this->plugin->gettext('status'));
         $table->add_header('options', null);
 
         $input    = new html_inputfield(array('name' => 'participant', 'id' => 'invitation-editor-name', 'size' => 30, 'class' => 'form-control'));
         $textarea = new html_textarea(array('name' => 'comment', 'id' => 'invitation-comment',
             'rows' => 4, 'cols' => 55, 'class' => 'form-control', 'title' => $this->plugin->gettext('invitationtexttitle')));
         $button   = new html_inputfield(array('type' => 'button', 'class' => 'button', 'id' => 'invitation-editor-add',
             'value' => $this->plugin->gettext('addparticipant')));
 
         $this->plugin->add_label('manageeditors', 'statusorganizer', 'addparticipant');
 
         // initialize attendees autocompletion
         $this->rc->autocomplete_init();
 
         return html::div(null, $table->show() . html::div(null,
             html::div('form-searchbar', $input->show() . " " . $button->show())
             . html::p('attendees-commentbox', html::label(null,
                 $this->plugin->gettext('invitationtextlabel') . $textarea->show())
             )
         ));
     }
 
     /**
      * Template object for file_rename form
      */
     public function file_rename_form($attrib)
     {
         $attrib['name'] = 'file-rename-form';
         if (empty($attrib['id'])) {
             $attrib['id'] = 'file-rename-form';
         }
 
         $input_name = new html_inputfield(array('id' => 'file-rename-name', 'name' => 'name', 'size' => 50));
         $table      = new html_table(array('cols' => 2, 'class' => 'propform'));
 
         $table->add('title', html::label('file-rename-name', rcube::Q($this->plugin->gettext('filename'))));
         $table->add(null, $input_name->show());
 
         $out = $table->show();
 
         // add form tag around text field
         if (empty($attrib['form'])) {
             $out = $this->rc->output->form_tag($attrib, $out);
         }
 
         $this->plugin->add_label('save', 'cancel', 'fileupdating', 'renamefile');
         $this->rc->output->add_gui_object('file-rename-form', $attrib['id']);
 
         return $out;
     }
 
     /**
      * Template object for file_create form
      */
     public function file_create_form($attrib)
     {
         $attrib['name'] = 'file-create-form';
         if (empty($attrib['id'])) {
             $attrib['id'] = 'file-create-form';
         }
 
         $input_name    = new html_inputfield(array('id' => 'file-create-name', 'name' => 'name', 'size' => 30));
         $select_parent = new html_select(array('id' => 'file-create-parent', 'name' => 'parent'));
         $select_type   = new html_select(array('id' => 'file-create-type', 'name' => 'type'));
         $table         = new html_table(array('cols' => 2, 'class' => 'propform'));
 
         $types = array();
 
         foreach ($this->get_mimetypes('edit') as $type => $mimetype) {
             $types[$type] = $mimetype['ext'];
             $select_type->add($mimetype['label'], $type);
         }
 
         $table->add('title', html::label('file-create-name', rcube::Q($this->plugin->gettext('filename'))));
         $table->add(null, $input_name->show());
         $table->add('title', html::label('file-create-type', rcube::Q($this->plugin->gettext('type'))));
         $table->add(null, $select_type->show());
         $table->add('title', html::label('file-create-parent', rcube::Q($this->plugin->gettext('folderinside'))));
         $table->add(null, $select_parent->show());
 
         $out = $table->show();
 
         // add form tag around text field
         if (empty($attrib['form'])) {
             $out = $this->rc->output->form_tag($attrib, $out);
         }
 
         $this->plugin->add_label('create', 'cancel', 'filecreating', 'createfile', 'createandedit',
             'copyfile', 'copyandedit');
         $this->rc->output->add_gui_object('file-create-form', $attrib['id']);
         $this->rc->output->set_env('file_extensions', $types);
 
         return $out;
     }
 
     /**
      * Template object for file search form in "From cloud" dialog
      */
     public function file_search_form($attrib)
     {
         $attrib += array(
             'name'          => '_q',
             'gui-object'    => 'filesearchbox',
             'form-name'     => 'filesearchform',
             'command'       => 'files-search',
             'reset-command' => 'files-search-reset',
         );
 
         // add form tag around text field
         return $this->rc->output->search_form($attrib);
     }
 
     /**
      * Template object for files list
      */
     public function file_list($attrib)
     {
         return $this->list_handler($attrib, 'files');
     }
 
     /**
      * Template object for sessions list
      */
     public function sessions_list($attrib)
     {
         return $this->list_handler($attrib, 'sessions');
     }
 
     /**
      * Creates unified template object for files|sessions list
      */
     protected function list_handler($attrib, $type = 'files')
     {
         $prefix   = 'kolab_' . $type . '_';
         $c_prefix = 'kolab_files' . ($type != 'files' ? '_' . $type : '') . '_';
 
         // define list of cols to be displayed based on parameter or config
         if (empty($attrib['columns'])) {
             $list_cols     = $this->rc->config->get($c_prefix . 'list_cols');
             $dont_override = $this->rc->config->get('dont_override');
             $a_show_cols = is_array($list_cols) ? $list_cols : array('name');
             $this->rc->output->set_env($type . '_col_movable', !in_array($c_prefix . 'list_cols', (array)$dont_override));
         }
         else {
             $columns     = str_replace(array("'", '"'), '', $attrib['columns']);
             $a_show_cols = preg_split('/[\s,;]+/', $columns);
         }
 
         // make sure 'name' and 'options' column is present
         if (!in_array('name', $a_show_cols)) {
             array_unshift($a_show_cols, 'name');
         }
         if (!in_array('options', $a_show_cols)) {
             array_unshift($a_show_cols, 'options');
         }
 
         $attrib['columns'] = $a_show_cols;
 
         // save some variables for use in ajax list
         $_SESSION[$prefix . 'list_attrib'] = $attrib;
 
         // For list in dialog(s) remove all option-like columns
         if ($this->rc->task != 'files') {
             $a_show_cols = array_intersect($a_show_cols, $this->{$type . '_sort_cols'});
         }
 
         // set default sort col/order to session
         if (!isset($_SESSION[$prefix . 'sort_col']))
             $_SESSION[$prefix . 'sort_col'] = $this->rc->config->get($c_prefix . 'sort_col') ?: 'name';
         if (!isset($_SESSION[$prefix . 'sort_order']))
             $_SESSION[$prefix . 'sort_order'] = strtoupper($this->rc->config->get($c_prefix . 'sort_order') ?: 'asc');
 
         // set client env
         $this->rc->output->add_gui_object($type . 'list', $attrib['id']);
         $this->rc->output->set_env($type . '_sort_col', $_SESSION[$prefix . 'sort_col']);
         $this->rc->output->set_env($type . '_sort_order', $_SESSION[$prefix . 'sort_order']);
         $this->rc->output->set_env($type . '_coltypes', $a_show_cols);
 
         $this->rc->output->include_script('list.js');
 
         $this->rc->output->add_label('kolab_files.abort', 'searching');
 
         // attach css rules for mimetype icons
         if (!$this->filetypes_style) {
             $this->plugin->include_stylesheet($this->url . '/skins/default/images/mimetypes/style.css');
             $this->filetypes_style = true;
         }
 
         $thead = '';
         foreach ($this->list_head($attrib, $a_show_cols, $type) as $cell) {
             $thead .= html::tag('th', array('class' => $cell['className'], 'id' => $cell['id']), $cell['html']);
         }
 
         return html::tag('table', $attrib,
             html::tag('thead', null, html::tag('tr', null, $thead)) . html::tag('tbody', null, ''),
             array('style', 'class', 'id', 'cellpadding', 'cellspacing', 'border', 'summary'));
     }
 
     /**
      * Creates <THEAD> for message list table
      */
     protected function list_head($attrib, $a_show_cols, $type = 'files')
     {
         $prefix    = 'kolab_' . $type . '_';
         $c_prefix  = 'kolab_files_' . ($type != 'files' ? $type : '') . '_';
-        $skin_path = $_SESSION['skin_path'];
+        $skin_path = $_SESSION['skin_path'] ?? null;
 
         // check to see if we have some settings for sorting
         $sort_col   = $_SESSION[$prefix . 'sort_col'];
         $sort_order = $_SESSION[$prefix . 'sort_order'];
 
         $dont_override  = (array)$this->rc->config->get('dont_override');
         $disabled_sort  = in_array($c_prefix . 'sort_col', $dont_override);
         $disabled_order = in_array($c_prefix . 'sort_order', $dont_override);
 
         $this->rc->output->set_env($prefix . 'disabled_sort_col', $disabled_sort);
         $this->rc->output->set_env($prefix . 'disabled_sort_order', $disabled_order);
 
         // define sortable columns
         if ($disabled_sort)
             $a_sort_cols = $sort_col && !$disabled_order ? array($sort_col) : array();
         else
             $a_sort_cols = $this->{$type . '_sort_cols'};
 
         if (!empty($attrib['optionsmenuicon'])) {
             $onclick = 'return ' . rcmail_output::JS_OBJECT_NAME . ".command('menu-open', '{$type}listmenu', this, event)";
             $inner   = $this->rc->gettext('listoptions');
 
             if (is_string($attrib['optionsmenuicon']) && $attrib['optionsmenuicon'] != 'true') {
                 $inner = html::img(array('src' => $skin_path . $attrib['optionsmenuicon'], 'alt' => $this->rc->gettext('listoptions')));
             }
 
             $list_menu = html::a(array(
                 'href'     => '#list-options',
                 'onclick'  => $onclick,
                 'class'    => 'listmenu',
                 'id'       => $type . 'listmenulink',
                 'title'    => $this->rc->gettext('listoptions'),
                 'tabindex' => '0',
             ), $inner);
         }
         else {
             $list_menu = '';
         }
 
         $cells = array();
 
         foreach ($a_show_cols as $col) {
             // get column name
             switch ($col) {
             case 'options':
                 $col_name = $list_menu;
                 break;
             default:
                 $col_name = rcube::Q($this->plugin->gettext($col));
             }
 
             // make sort links
             if (in_array($col, $a_sort_cols)) {
                 $col_name = html::a(array(
                         'href'    => "#sort",
                         'onclick' => 'return ' . rcmail_output::JS_OBJECT_NAME . ".command('$type-sort','$col',this)",
                         'title'   => $this->plugin->gettext('sortby')
                     ), $col_name);
             }
-            else if ($col_name[0] != '<') {
+            else if (empty($col_name) || $col_name[0] != '<') {
                 $col_name = '<span class="' . $col .'">' . $col_name . '</span>';
             }
 
             $sort_class = $col == $sort_col && !$disabled_order ? " sorted$sort_order" : '';
             $class_name = $col.$sort_class;
 
             // put it all together
             $cells[] = array('className' => $class_name, 'id' => "rcm$col", 'html' => $col_name);
         }
 
         return $cells;
     }
 
     /**
      * Update files|sessions list object
      */
     protected function list_update($prefs, $type = 'files')
     {
         $prefix   = 'kolab_' . $type . '_list_';
         $c_prefix = 'kolab_files' . ($type != 'files' ? '_' . $type : '') . '_list_';
         $attrib   = $_SESSION[$prefix . 'attrib'];
 
         if (!empty($prefs[$c_prefix . 'cols'])) {
             $attrib['columns'] = $prefs[$c_prefix . 'cols'];
             $_SESSION[$prefix . 'attrib'] = $attrib;
         }
 
         $a_show_cols = $attrib['columns'];
         $head        = '';
 
         foreach ($this->list_head($attrib, $a_show_cols, $type) as $cell) {
             $head .= html::tag('th', array('class' => $cell['className'], 'id' => $cell['id']), $cell['html']);
         }
 
         $head = html::tag('tr', null, $head);
 
         $this->rc->output->set_env($type . '_coltypes', $a_show_cols);
         $this->rc->output->command($type . '_list_update', $head);
     }
 
     /**
      * Template object for file info box
      */
     public function file_info_box($attrib)
     {
         // print_r($this->file_data, true);
         $table = new html_table(array('cols' => 2, 'class' => $attrib['class']));
 
         // file name
         $table->add('title', $this->plugin->gettext('name').':');
         $table->add('data filename', $this->file_data['name']);
 
         // file type
         // @TODO: human-readable type name
         $table->add('title', $this->plugin->gettext('type').':');
         $table->add('data filetype', $this->file_data['type']);
 
         // file size
         $table->add('title', $this->plugin->gettext('size').':');
         $table->add('data filesize', $this->rc->show_bytes($this->file_data['size']));
 
         // file modification time
         $table->add('title', $this->plugin->gettext('mtime').':');
         $table->add('data filemtime', $this->file_data['mtime']);
 
         // @TODO: for images: width, height, color depth, etc.
         // @TODO: for text files: count of characters, lines, words
 
         return $table->show();
     }
 
     /**
      * Template object for file preview frame
      */
     public function file_preview_frame($attrib)
     {
         if (empty($attrib['id'])) {
             $attrib['id'] = 'filepreviewframe';
         }
 
         if ($frame = $this->file_data['viewer']['frame']) {
             return $frame;
         }
 
         if ($href = $this->file_data['viewer']['href']) {
             // file href attribute must be an absolute URL (Bug #2063)
             if (!empty($href)) {
                 if (!preg_match('|^https?://|', $href)) {
                     $href = $this->url . '/api/' . $href;
                 }
             }
         }
         else {
             $token = $this->get_api_token();
             $href  = $this->url . '/api/?method=file_get'
                 . '&file=' . urlencode($this->file_data['filename'])
                 . '&token=' . urlencode($token);
         }
 
         $this->rc->output->add_gui_object('preview_frame', $attrib['id']);
 
         $attrib['allowfullscreen'] = true;
         $attrib['src']             = $href;
         $attrib['onload']          = 'kolab_files_frame_load(this)';
 
         // editor requires additional arguments via POST
         if (!empty($this->file_data['viewer']['post'])) {
             $attrib['src'] = 'program/resources/blank.gif';
 
             $form_content = new html_hiddenfield();
             $form_attrib  = array(
                 'action' => $href,
                 'id'     => $attrib['id'] . '-form',
                 'target' => $attrib['name'],
                 'method' => 'post',
             );
 
             foreach ($this->file_data['viewer']['post'] as $name => $value) {
                 $form_content->add(array('name' => $name, 'value' => $value));
             }
 
             $form = html::tag('form', $form_attrib, $form_content->show())
                 . html::script(array(), "\$('#{$attrib['id']}-form').submit()");
         }
 
         return html::iframe($attrib) . $form;
     }
 
     /**
      * Template object for quota display
      */
     public function quota_display($attrib)
     {
         if (!$attrib['id']) {
             $attrib['id'] = 'rcmquotadisplay';
         }
 
         $quota_type = !empty($attrib['display']) ? $attrib['display'] : 'text';
 
         $this->rc->output->add_gui_object('quotadisplay', $attrib['id']);
         $this->rc->output->set_env('quota_type', $quota_type);
 
         // get quota
         $token   = $this->get_api_token();
         $request = $this->get_request(array('method' => 'quota'), $token);
 
         // send request to the API
         try {
             $response = $request->send();
             $status   = $response->getStatus();
             $body     = @json_decode($response->getBody(), true);
 
             if ($status == 200 && $body['status'] == 'OK') {
                 $quota = $body['result'];
             }
             else {
                 throw new Exception($body['reason'] ?: "Failed to get quota. Status: $status");
             }
         }
         catch (Exception $e) {
             rcube::raise_error($e, true, false);
             $quota = array('total' => 0, 'percent' => 0);
         }
 
         $quota = rcube_output::json_serialize($quota);
 
         $this->rc->output->add_script(rcmail_output::JS_OBJECT_NAME . ".files_set_quota($quota);", 'docready');
 
         return html::span($attrib, '');
     }
 
     /**
      * Get API token for current user session, authenticate if needed
      */
     public function get_api_token($configure = true)
     {
         $token = $_SESSION['kolab_files_token'];
         $time  = $_SESSION['kolab_files_time'];
 
         if ($token && time() - $this->timeout < $time) {
             if (time() - $time <= $this->timeout / 2) {
                 return $token;
             }
         }
 
         $request = $this->get_request(array('method' => 'ping'), $token);
 
         try {
             $url = $request->getUrl();
 
             // Send ping request
             if ($token) {
                 $url->setQueryVariables(array('method' => 'ping'));
                 $request->setUrl($url);
                 $response = $request->send();
                 $status   = $response->getStatus();
 
                 if ($status == 200 && ($body = json_decode($response->getBody(), true))) {
                     if ($body['status'] == 'OK') {
                         $_SESSION['kolab_files_time']  = time();
                         return $token;
                     }
                 }
             }
 
             // Go with authenticate request
             $url->setQueryVariables(array('method' => 'authenticate', 'version' => self::API_VERSION));
             $request->setUrl($url);
             $request->setAuth($this->rc->user->get_username(), $this->rc->decrypt($_SESSION['password']));
 
             // Allow plugins (e.g. kolab_sso) to modify the request
             $this->rc->plugins->exec_hook('chwala_authenticate', array('request' => $request));
 
             $response = $request->send();
             $status   = $response->getStatus();
 
             if ($status == 200 && ($body = json_decode($response->getBody(), true))) {
                 $token = $body['result']['token'];
 
                 if ($token) {
                     $_SESSION['kolab_files_token'] = $token;
                     $_SESSION['kolab_files_time']  = time();
                     $_SESSION['kolab_files_caps']  = $body['result']['capabilities'];
                 }
             }
             else {
                 throw new Exception(sprintf("Authenticate error (Status: %d)", $status));
             }
 
             // Configure session
             if ($configure && $token) {
                 $this->configure($token);
             }
         }
         catch (Exception $e) {
             rcube::raise_error($e, true, false);
         }
 
         return $token;
     }
 
     protected function capabilities()
     {
         if (empty($_SESSION['kolab_files_caps'])) {
             $token = $this->get_api_token();
 
             if (empty($_SESSION['kolab_files_caps'])) {
                 $request = $this->get_request(array('method' => 'capabilities'), $token);
 
                 // send request to the API
                 try {
                     $response = $request->send();
                     $status   = $response->getStatus();
                     $body     = @json_decode($response->getBody(), true);
 
                     if ($status == 200 && $body['status'] == 'OK') {
                         $_SESSION['kolab_files_caps'] = $body['result'];
                     }
                     else {
                         throw new Exception($body['reason'] ?: "Failed to get capabilities. Status: $status");
                     }
                 }
                 catch (Exception $e) {
                     rcube::raise_error($e, true, false);
                     return array();
                 }
             }
         }
 
-        if ($_SESSION['kolab_files_caps']['MANTICORE'] || $_SESSION['kolab_files_caps']['WOPI']) {
+        if (($_SESSION['kolab_files_caps']['MANTICORE'] ?? false) || ($_SESSION['kolab_files_caps']['WOPI'] ?? false)) {
             $_SESSION['kolab_files_caps']['DOCEDIT'] = true;
             $_SESSION['kolab_files_caps']['DOCTYPE'] = $_SESSION['kolab_files_caps']['MANTICORE'] ? 'manticore' : 'wopi';
         }
 
         if (!empty($_SESSION['kolab_files_caps']) && !isset($_SESSION['kolab_files_caps']['MOUNTPOINTS'])) {
             $_SESSION['kolab_files_caps']['MOUNTPOINTS'] = array();
         }
 
         return $_SESSION['kolab_files_caps'];
     }
 
     /**
      * Initialize HTTP_Request object
      */
     protected function get_request($get = null, $token = null)
     {
         $url = $this->url_srv . '/api/';
 
         if (!$this->request) {
             $config = array(
                 'store_body'       => true,
                 'follow_redirects' => true,
             );
 
             $this->request = libkolab::http_request($url, 'GET', $config);
         }
         else {
             // cleanup
             try {
                 $this->request->setBody('');
                 $this->request->setUrl($url);
                 $this->request->setMethod(HTTP_Request2::METHOD_GET);
             }
             catch (Exception $e) {
                 rcube::raise_error($e, true, true);
             }
         }
 
         if ($token) {
             $this->request->setHeader('X-Session-Token', $token);
         }
 
         if (!empty($get)) {
             $url = $this->request->getUrl();
             $url->setQueryVariables($get);
             $this->request->setUrl($url);
         }
 
         // some HTTP server configurations require this header
         $this->request->setHeader('accept', "application/json,text/javascript,*/*");
 
         // Localization
         $this->request->setHeader('accept-language', $_SESSION['language']);
 
         // set Referer which is used as an origin for cross-window
         // communication with document editor iframe
         $host = $_SERVER['REQUEST_SCHEME'] . '://' . $_SERVER['HTTP_HOST'];
         $this->request->setHeader('referer', $host);
 
         return $this->request;
     }
 
     /**
      * Configure chwala session
      */
     public function configure($token = null, $prefs = array())
     {
         if (!$token) {
             $token = $this->get_api_token(false);
         }
 
         try {
             // Configure session
             $query = array(
                 'method'      => 'configure',
-                'timezone'    => $prefs['timezone'] ?: $this->rc->config->get('timezone'),
-                'date_format' => $prefs['date_long'] ?: $this->rc->config->get('date_long', 'Y-m-d H:i'),
+                'timezone'    => $prefs['timezone'] ?? $this->rc->config->get('timezone'),
+                'date_format' => $prefs['date_long'] ?? $this->rc->config->get('date_long', 'Y-m-d H:i'),
             );
 
             $request  = $this->get_request($query, $token);
             $response = $request->send();
             $status   = $response->getStatus();
 
             if ($status != 200) {
                 throw new Exception(sprintf("Failed to configure chwala session (Status: %d)", $status));
             }
         }
         catch (Exception $e) {
             rcube::raise_error($e, true, false);
         }
     }
 
     /**
      * Handler for main files interface (Files task)
      */
     protected function action_index()
     {
         $this->plugin->add_label(
             'uploading', 'attaching', 'uploadsizeerror',
             'filedeleting', 'filedeletenotice', 'filedeleteconfirm',
             'filemoving', 'filemovenotice', 'filemoveconfirm', 'filecopying', 'filecopynotice',
             'fileskip', 'fileskipall', 'fileoverwrite', 'fileoverwriteall'
         );
 
         $this->folder_list_env();
 
         if ($this->rc->task == 'files') {
             $this->rc->output->set_env('folder', rcube_utils::get_input_value('folder', rcube_utils::INPUT_GET));
             $this->rc->output->set_env('collection', rcube_utils::get_input_value('collection', rcube_utils::INPUT_GET));
         }
 
         $caps = $this->capabilities();
 
         $this->rc->output->add_label('uploadprogress', 'GB', 'MB', 'KB', 'B');
         $this->rc->output->set_pagetitle($this->plugin->gettext('files'));
         $this->rc->output->set_env('file_mimetypes', $this->get_mimetypes());
         $this->rc->output->set_env('files_quota', $caps['QUOTA']);
         $this->rc->output->set_env('files_max_upload', $caps['MAX_UPLOAD']);
         $this->rc->output->set_env('files_progress_name', $caps['PROGRESS_NAME']);
         $this->rc->output->set_env('files_progress_time', $caps['PROGRESS_TIME']);
         $this->rc->output->send('kolab_files.files');
     }
 
     /**
      * Handler for resetting some session/cached information
      */
     protected function action_reset()
     {
         $this->rc->session->remove('kolab_files_caps');
         if (($caps = $this->capabilities()) && !empty($caps)) {
             $this->rc->output->set_env('files_caps', $caps);
         }
     }
 
     /**
      * Handler for preferences save action
      */
     protected function action_prefs()
     {
         $dont_override = (array)$this->rc->config->get('dont_override');
         $prefs = array();
         $type  = rcube_utils::get_input_value('type', rcube_utils::INPUT_POST);
         $opts  = array(
             'kolab_files_sort_col'   => true,
             'kolab_files_sort_order' => true,
             'kolab_files_list_cols'  => false,
         );
 
         foreach ($opts as $o => $sess) {
             if (isset($_POST[$o])) {
                 $value       = rcube_utils::get_input_value($o, rcube_utils::INPUT_POST);
                 $session_key = $o;
                 $config_key  = $o;
 
                 if ($type != 'files') {
                     $config_key = str_replace('files', 'files_' . $type, $config_key);
                 }
 
                 if (in_array($config_key, $dont_override)) {
                     continue;
                 }
 
                 if ($o == 'kolab_files_list_cols') {
                     $update_list = true;
                 }
 
                 $prefs[$config_key] = $value;
                 if ($sess) {
                     $_SESSION[$session_key] = $prefs[$config_key];
                 }
             }
         }
 
         // save preference values
         if (!empty($prefs)) {
             $this->rc->user->save_prefs($prefs);
         }
 
         if (!empty($update_list)) {
             $this->list_update($prefs, $type);
         }
 
         $this->rc->output->send();
     }
 
     /**
      * Handler for file open action
      */
     protected function action_open()
     {
         $this->rc->output->set_env('file_mimetypes', $this->get_mimetypes());
 
         $this->file_opener(intval($_GET['_viewer']) & ~4);
     }
 
     /**
      * Handler for file open action
      */
     protected function action_edit()
     {
         $this->plugin->add_label('sessionterminating', 'unsavedchanges', 'documentinviting',
             'documentcancelling', 'removeparticipant', 'sessionterminated', 'sessionterminatedtitle');
 
         $this->file_opener(intval($_GET['_viewer']));
     }
 
     /**
      * Handler for folder sharing action
      */
     protected function action_share()
     {
         $this->rc->output->add_handler('share-form', array($this, 'folder_share_form'));
 
         $this->rc->output->send('kolab_files.share');
     }
 
     /**
      * Handler for "save all attachments into cloud" action
      */
     protected function action_save_file()
     {
 //        $source = rcube_utils::get_input_value('source', rcube_utils::INPUT_POST);
         $uid    = rcube_utils::get_input_value('uid', rcube_utils::INPUT_POST);
         $dest   = rcube_utils::get_input_value('dest', rcube_utils::INPUT_POST);
         $id     = rcube_utils::get_input_value('id', rcube_utils::INPUT_POST);
         $name   = rcube_utils::get_input_value('name', rcube_utils::INPUT_POST);
 
         $temp_dir = unslashify($this->rc->config->get('temp_dir'));
         $message  = new rcube_message($uid);
         $request  = $this->get_request();
         $url      = $request->getUrl();
         $files    = array();
         $errors   = array();
         $attachments = array();
 
         $request->setMethod(HTTP_Request2::METHOD_POST);
         $request->setHeader('X-Session-Token', $this->get_api_token());
         $url->setQueryVariables(array('method' => 'file_upload', 'folder' => $dest));
         $request->setUrl($url);
 
         foreach ($message->attachments as $attach_prop) {
             if (empty($id) || $id == $attach_prop->mime_id) {
                 $filename = strlen($name) ? $name : rcmail_attachment_name($attach_prop, true);
                 $attachments[$filename] = $attach_prop;
             }
         }
 
         // @TODO: handle error
         // @TODO: implement file upload using file URI instead of body upload
 
         foreach ($attachments as $attach_name => $attach_prop) {
             $path = tempnam($temp_dir, 'rcmAttmnt');
 
             // save attachment to file
             if ($fp = fopen($path, 'w+')) {
                 $message->get_part_body($attach_prop->mime_id, false, 0, $fp);
             }
             else {
                 $errors[] = true;
                 rcube::raise_error(array(
                     'code' => 500, 'type' => 'php', 'line' => __LINE__, 'file' => __FILE__,
                     'message' => "Unable to save attachment into file $path"),
                     true, false);
                 continue;
             }
 
             fclose($fp);
 
             // send request to the API
             try {
                 $request->setBody('');
                 $request->addUpload('file[]', $path, $attach_name, $attach_prop->mimetype);
                 $response = $request->send();
                 $status   = $response->getStatus();
                 $body     = @json_decode($response->getBody(), true);
 
                 if ($status == 200 && $body['status'] == 'OK') {
                     $files[] = $attach_name;
                 }
                 else {
                     throw new Exception($body['reason'] ?: "Failed to post file_upload. Status: $status");
                 }
             }
             catch (Exception $e) {
                 unlink($path);
                 $errors[] = $e->getMessage();
                 rcube::raise_error(array(
                     'code' => 500, 'type' => 'php', 'line' => __LINE__, 'file' => __FILE__,
                     'message' => $e->getMessage()),
                     true, false);
                 continue;
             }
 
             // clean up
             unlink($path);
             $request->setBody('');
         }
 
         if ($count = count($files)) {
             $msg = $this->plugin->gettext(array('name' => 'saveallnotice', 'vars' => array('n' => $count)));
             $this->rc->output->show_message($msg, 'confirmation');
         }
         if ($count = count($errors)) {
             $msg = $this->plugin->gettext(array('name' => 'saveallerror', 'vars' => array('n' => $count)));
             $this->rc->output->show_message($msg, 'error');
         }
 
         // @TODO: update quota indicator, make this optional in case files aren't stored in IMAP
 
         $this->rc->output->send();
     }
 
     /**
      * Handler for "add attachments from the cloud" action
      */
     protected function action_attach_file()
     {
         $files       = rcube_utils::get_input_value('files', rcube_utils::INPUT_POST);
         $uploadid    = rcube_utils::get_input_value('uploadid', rcube_utils::INPUT_POST);
         $COMPOSE_ID  = rcube_utils::get_input_value('id', rcube_utils::INPUT_POST);
         $COMPOSE     = null;
         $errors      = array();
         $attachments = array();
 
         if ($this->rc->task == 'mail') {
             if ($COMPOSE_ID && $_SESSION['compose_data_'.$COMPOSE_ID]) {
                 $COMPOSE =& $_SESSION['compose_data_'.$COMPOSE_ID];
             }
 
             if (!$COMPOSE) {
                 die("Invalid session var!");
             }
 
             // attachment upload action
             if (!is_array($COMPOSE['attachments'])) {
                 $COMPOSE['attachments'] = array();
             }
         }
 
         // clear all stored output properties (like scripts and env vars)
         $this->rc->output->reset();
 
         $temp_dir = unslashify($this->rc->config->get('temp_dir'));
         $request  = $this->get_request();
         $url      = $request->getUrl();
 
         // Use observer object to store HTTP response into a file
         require_once $this->plugin->home . DIRECTORY_SEPARATOR . 'lib' . DIRECTORY_SEPARATOR . 'kolab_files_observer.php';
         $observer = new kolab_files_observer();
 
         $request->setHeader('X-Session-Token', $this->get_api_token());
 
         // download files from the API and attach them
         foreach ($files as $file) {
             // decode filename
             $file = urldecode($file);
 
             // get file information
             try {
                 $url->setQueryVariables(array('method' => 'file_info', 'file' => $file));
                 $request->setUrl($url);
                 $response = $request->send();
                 $status   = $response->getStatus();
                 $body     = @json_decode($response->getBody(), true);
 
                 if ($status == 200 && $body['status'] == 'OK') {
                     $file_params = $body['result'];
                 }
                 else {
                     throw new Exception($body['reason'] ?: "Failed to get file_info. Status: $status");
                 }
             }
             catch (Exception $e) {
                 $errors[] = $e->getMessage();
                 rcube::raise_error(array(
                     'code' => 500, 'type' => 'php', 'line' => __LINE__, 'file' => __FILE__,
                     'message' => $e->getMessage()),
                     true, false);
                 continue;
             }
 
             // set location of downloaded file
             $path = tempnam($temp_dir, 'rcmAttmnt');
             $observer->set_file($path);
 
             // download file
             try {
                 $url->setQueryVariables(array('method' => 'file_get', 'file' => $file));
                 $request->setUrl($url);
                 $request->attach($observer);
                 $response = $request->send();
                 $status   = $response->getStatus();
                 $response->getBody(); // returns nothing
                 $request->detach($observer);
 
                 if ($status != 200 || !file_exists($path)) {
                     throw new Exception("Unable to save file");
                 }
             }
             catch (Exception $e) {
                 $errors[] = $e->getMessage();
                 rcube::raise_error(array(
                     'code' => 500, 'type' => 'php', 'line' => __LINE__, 'file' => __FILE__,
                     'message' => $e->getMessage()),
                     true, false);
                 continue;
             }
 
             $attachment = array(
                 'path'     => $path,
                 'size'     => $file_params['size'],
                 'name'     => $file_params['name'],
                 'mimetype' => $file_params['type'],
                 'group'    => $COMPOSE_ID,
             );
 
             if ($this->rc->task != 'mail') {
                 $attachments[] = $attachment;
                 continue;
             }
 
             $attachment = $this->rc->plugins->exec_hook('attachment_save', $attachment);
 
             if ($attachment['status'] && !$attachment['abort']) {
                 $this->compose_attach_success($attachment, $COMPOSE, $COMPOSE_ID, $uploadid);
             }
             else if ($attachment['error']) {
                 $errors[] = $attachment['error'];
             }
             else {
                 $errors[] = $this->plugin->gettext('attacherror');
             }
         }
 
         if (!empty($errors)) {
             $this->rc->output->command('display_message', $this->plugin->gettext('attacherror'), 'error');
             $this->rc->output->command('remove_from_attachment_list', $uploadid);
         }
         else if ($this->rc->task == 'calendar' || $this->rc->task == 'tasks') {
             // for uploads in events/tasks we'll use its standard upload handler,
             // for this we have to fake $_FILES and some other POST args
             foreach ($attachments as $attach) {
                 $_FILES['_attachments']['tmp_name'][] = $attachment['path'];
                 $_FILES['_attachments']['name'][]     = $attachment['name'];
                 $_FILES['_attachments']['size'][]     = $attachment['size'];
                 $_FILES['_attachments']['type'][]     = $attachment['mimetype'];
                 $_FILES['_attachments']['error'][]    = null;
             }
 
             $_GET['_uploadid'] = $uploadid;
             $_GET['_id']       = $COMPOSE_ID;
 
             switch ($this->rc->task) {
             case 'tasks':
                 $handler = new kolab_attachments_handler();
                 $handler->attachment_upload(tasklist::SESSION_KEY);
                 break;
 
             case 'calendar':
                 $handler = new kolab_attachments_handler();
                 $handler->attachment_upload(calendar::SESSION_KEY, 'cal-');
                 break;
             }
         }
 
         // send html page with JS calls as response
         $this->rc->output->command('auto_save_start', false);
         $this->rc->output->send();
     }
 
     protected function compose_attach_success($attachment, $COMPOSE, $COMPOSE_ID, $uploadid)
     {
         $id = $attachment['id'];
 
         // store new attachment in session
         unset($attachment['data'], $attachment['status'], $attachment['abort']);
         $this->rc->session->append('compose_data_' . $COMPOSE_ID . '.attachments', $id, $attachment);
 
         if (($icon = $COMPOSE['deleteicon']) && is_file($icon)) {
             $button = html::img(array(
                 'src' => $icon,
                 'alt' => $this->rc->gettext('delete')
             ));
         }
         else if ($COMPOSE['textbuttons']) {
             $button = rcube::Q($this->rc->gettext('delete'));
         }
         else {
             $button = '';
         }
 
         if (version_compare(version_parse(RCMAIL_VERSION), '1.3.0', '>=')) {
             $link_content = sprintf('%s <span class="attachment-size"> (%s)</span>',
                 rcube::Q($attachment['name']), $this->rc->show_bytes($attachment['size']));
 
             $content_link = html::a(array(
                     'href'    => "#load",
                     'class'   => 'filename',
                     'onclick' => sprintf("return %s.command('load-attachment','rcmfile%s', this, event)", rcmail_output::JS_OBJECT_NAME, $id),
                 ), $link_content);
 
             $delete_link = html::a(array(
                     'href'    => "#delete",
                     'onclick' => sprintf("return %s.command('remove-attachment','rcmfile%s', this, event)", rcmail_output::JS_OBJECT_NAME, $id),
                     'title'   => $this->rc->gettext('delete'),
                     'class'   => 'delete',
                     'aria-label' => $this->rc->gettext('delete') . ' ' . $attachment['name'],
                 ), $button);
 
             $content = $COMPOSE['icon_pos'] == 'left' ? $delete_link.$content_link : $content_link.$delete_link;
         }
         else {
             $content = html::a(array(
                     'href'    => "#delete",
                     'onclick' => sprintf("return %s.command('remove-attachment','rcmfile%s', this)", rcmail_output::JS_OBJECT_NAME, $id),
                     'title'   => $this->rc->gettext('delete'),
                     'class'   => 'delete',
             ), $button);
 
             $content .= rcube::Q($attachment['name']);
         }
 
         $this->rc->output->command('add2attachment_list', "rcmfile$id", array(
             'html'      => $content,
             'name'      => $attachment['name'],
             'mimetype'  => $attachment['mimetype'],
             'classname' => rcube_utils::file2class($attachment['mimetype'], $attachment['name']),
             'complete'  => true), $uploadid);
     }
 
     /**
      * Handler for file open/edit action
      */
     protected function file_opener($viewer)
     {
         $file    = rcube_utils::get_input_value('_file', rcube_utils::INPUT_GET);
         $session = rcube_utils::get_input_value('_session', rcube_utils::INPUT_GET);
 
         // get file info
         $token   = $this->get_api_token();
         $request = $this->get_request(array(
             'method'  => 'file_info',
             'file'    => $file,
             'viewer'  => $viewer,
             'session' => $session,
             ), $token);
 
         // send request to the API
         try {
             $response = $request->send();
             $status   = $response->getStatus();
             $body     = @json_decode($response->getBody(), true);
 
             if ($status == 200 && $body['status'] == 'OK') {
                 $this->file_data = $body['result'];
             }
             else {
                 throw new Exception($body['reason'] ?: "Failed to get file_info. Status: $status");
             }
         }
         catch (Exception $e) {
             rcube::raise_error(array(
                 'code' => 500, 'type' => 'php', 'line' => __LINE__, 'file' => __FILE__,
                 'message' => $e->getMessage()),
                 true, true);
         }
 
         if ($file === null || $file === '') {
             $file = $this->file_data['file'];
         }
 
         $this->file_data['filename'] = $file;
 
         $this->plugin->add_label('filedeleteconfirm', 'filedeleting', 'filedeletenotice', 'terminate');
 
         // register template objects for dialogs (and main interface)
         $this->rc->output->add_handlers(array(
             'fileinfobox'      => array($this, 'file_info_box'),
             'filepreviewframe' => array($this, 'file_preview_frame'),
         ));
 
         $placeholder = $this->rc->output->asset_url('program/resources/blank.gif');
 
         if ($this->file_data['viewer']['wopi']) {
             $editor_type = 'wopi';
             $got_editor  = ($viewer & 4);
         }
         else if ($this->file_data['viewer']['manticore']) {
             $editor_type = 'manticore';
             $got_editor = ($viewer & 4);
         }
 
         // this one is for styling purpose
         $this->rc->output->set_env('extwin', true);
         $this->rc->output->set_env('file', $file);
         $this->rc->output->set_env('file_data', $this->file_data);
         $this->rc->output->set_env('mimetype', $this->file_data['type']);
         $this->rc->output->set_env('filename', pathinfo($file, PATHINFO_BASENAME));
         $this->rc->output->set_env('editor_type', $editor_type);
         $this->rc->output->set_env('photo_placeholder', $placeholder);
         $this->rc->output->set_pagetitle(rcube::Q($file));
         $this->rc->output->send('kolab_files.' . ($got_editor ? 'docedit' : 'filepreview'));
     }
 
     /**
      * Returns mimetypes supported by File API viewers
      */
     protected function get_mimetypes($type = 'view')
     {
         $mimetypes = array();
 
         // send request to the API
         try {
             if ($this->mimetypes === null) {
                 $this->mimetypes = false;
 
                 $token    = $this->get_api_token();
                 $caps     = $this->capabilities();
                 $request  = $this->get_request(array('method' => 'mimetypes'), $token);
                 $response = $request->send();
                 $status   = $response->getStatus();
                 $body     = @json_decode($response->getBody(), true);
 
                 if ($status == 200 && $body['status'] == 'OK') {
                     $this->mimetypes = $body['result'];
                 }
                 else {
                     throw new Exception($body['reason'] ?: "Failed to get mimetypes. Status: $status");
                 }
             }
 
             if (is_array($this->mimetypes)) {
                 if (array_key_exists($type, $this->mimetypes)) {
                     $mimetypes = $this->mimetypes[$type];
                 }
                 // fallback to static definition if old Chwala is used
                 else if ($type == 'edit') {
                     $mimetypes = array(
                         'text/plain' => 'txt',
                         'text/html'  => 'html',
                     );
                     if (!empty($caps['MANTICORE'])) {
                         $mimetypes = array_merge(array('application/vnd.oasis.opendocument.text' => 'odt'), $mimetypes);
                     }
 
                     foreach (array_keys($mimetypes) as $type) {
                         list ($app, $label) = explode('/', $type);
                         $label = preg_replace('/[^a-z]/', '', $label);
                         $mimetypes[$type] = array(
                             'ext'   => $mimetypes[$type],
                             'label' => $this->plugin->gettext('type.' . $label),
                         );
                     }
                 }
                 else {
                     $mimetypes = $this->mimetypes;
                 }
             }
         }
         catch (Exception $e) {
             rcube::raise_error(array(
                 'code' => 500, 'type' => 'php', 'line' => __LINE__, 'file' => __FILE__,
                 'message' => $e->getMessage()),
                 true, false);
         }
 
         return $mimetypes;
     }
 
     /**
      * Get list of available external storage drivers
      */
     protected function get_external_storage_drivers()
     {
         // first get configured sources from Chwala
         $token   = $this->get_api_token();
         $request = $this->get_request(array('method' => 'folder_types'), $token);
 
         // send request to the API
         try {
             $response = $request->send();
             $status   = $response->getStatus();
             $body     = @json_decode($response->getBody(), true);
 
             if ($status == 200 && $body['status'] == 'OK') {
                 $sources = $body['result'];
             }
             else {
                 throw new Exception($body['reason'] ?: "Failed to get folder_types. Status: $status");
             }
         }
         catch (Exception $e) {
             rcube::raise_error($e, true, false);
             return;
         }
 
         $this->rc->output->set_env('external_sources', $sources);
     }
 
     /**
      * Get folder share dialog data
      */
     protected function get_share_info($folder)
     {
         // first get configured sources from Chwala
         $token   = $this->get_api_token();
         $request = $this->get_request(array('method' => 'sharing', 'folder' => $folder), $token);
 
         // send request to the API
         try {
             $response = $request->send();
             $status   = $response->getStatus();
             $body     = @json_decode($response->getBody(), true);
 
             if ($status == 200 && $body['status'] == 'OK') {
                 $info = $body['result'];
             }
             else if ($body['code'] == 530) {
                 return false;
             }
             else {
                 throw new Exception($body['reason'] ?: "Failed to get sharing form information. Status: $status");
             }
         }
         catch (Exception $e) {
             rcube::raise_error($e, true, false);
             return;
         }
 
         return $info;
     }
 
     /**
      * Registers translation labels for folder lists in UI
      */
     protected function folder_list_env()
     {
         // folder list and actions
         $this->plugin->add_label(
             'folderdeleting', 'folderdeleteconfirm', 'folderdeletenotice',
             'collection_audio', 'collection_video', 'collection_image', 'collection_document',
             'additionalfolders', 'listpermanent', 'storageautherror'
         );
         $this->rc->output->add_label('foldersubscribing', 'foldersubscribed',
             'folderunsubscribing', 'folderunsubscribed', 'searching'
         );
     }
 }
diff --git a/plugins/kolab_notes/kolab_notes.php b/plugins/kolab_notes/kolab_notes.php
index 9d1c240d..0446e7cd 100644
--- a/plugins/kolab_notes/kolab_notes.php
+++ b/plugins/kolab_notes/kolab_notes.php
@@ -1,1482 +1,1482 @@
 <?php
 
 /**
  * Kolab notes module
  *
  * Adds simple notes management features to the web client
  *
  * @version @package_version@
  * @author Thomas Bruederli <bruederli@kolabsys.com>
  *
  * Copyright (C) 2014-2015, Kolab Systems AG <contact@kolabsys.com>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
  * published by the Free Software Foundation, either version 3 of the
  * License, or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU Affero General Public License for more details.
  *
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
 class kolab_notes extends rcube_plugin
 {
     public $task = '?(?!login|logout).*';
     public $allowed_prefs = array('kolab_notes_sort_col');
     public $rc;
 
     private $ui;
     private $lists;
     private $folders;
     private $cache = array();
     private $message_notes = array();
     private $bonnie_api = false;
 
     /**
      * Required startup method of a Roundcube plugin
      */
     public function init()
     {
         $this->require_plugin('libkolab');
 
         $this->rc = rcube::get_instance();
 
         // proceed initialization in startup hook
         $this->add_hook('startup', array($this, 'startup'));
     }
 
     /**
      * Startup hook
      */
     public function startup($args)
     {
         // the notes module can be enabled/disabled by the kolab_auth plugin
         if ($this->rc->config->get('kolab_notes_disabled', false) || !$this->rc->config->get('kolab_notes_enabled', true)) {
             return;
         }
 
         $this->register_task('notes');
 
         // load plugin configuration
         $this->load_config();
 
         // load localizations
         $this->add_texts('localization/', $args['task'] == 'notes' && (!$args['action'] || $args['action'] == 'dialog-ui'));
         $this->rc->load_language($_SESSION['language'], array('notes.notes' => $this->gettext('navtitle')));  // add label for task title
 
         if ($args['task'] == 'notes') {
             $this->add_hook('storage_init', array($this, 'storage_init'));
 
             // register task actions
             $this->register_action('index', array($this, 'notes_view'));
             $this->register_action('fetch', array($this, 'notes_fetch'));
             $this->register_action('get',   array($this, 'note_record'));
             $this->register_action('action', array($this, 'note_action'));
             $this->register_action('list',  array($this, 'list_action'));
             $this->register_action('dialog-ui', array($this, 'dialog_view'));
             $this->register_action('print', array($this, 'print_note'));
 
             if (!$this->rc->output->ajax_call && in_array($args['action'], array('dialog-ui', 'list'))) {
                 $this->load_ui();
             }
         }
         else if ($args['task'] == 'mail') {
             $this->add_hook('storage_init', array($this, 'storage_init'));
             $this->add_hook('message_compose', array($this, 'mail_message_compose'));
 
             if (in_array($args['action'], array('show', 'preview', 'print'))) {
                 $this->add_hook('message_load', array($this, 'mail_message_load'));
                 $this->add_hook('template_object_messagebody', array($this, 'mail_messagebody_html'));
             }
 
             // add 'Append note' item to message menu
-            if ($this->api->output->type == 'html' && $_REQUEST['_rel'] != 'note') {
+            if ($this->api->output->type == 'html' && ($_REQUEST['_rel'] ?? null) != 'note') {
                 $this->api->add_content(html::tag('li', array('role' => 'menuitem'),
                     $this->api->output->button(array(
                       'command'  => 'append-kolab-note',
                       'label'    => 'kolab_notes.appendnote',
                       'type'     => 'link',
                       'classact' => 'icon appendnote active',
                       'class'    => 'icon appendnote disabled',
                       'innerclass' => 'icon note',
                     ))),
                     'messagemenu');
 
                 $this->api->output->add_label('kolab_notes.appendnote', 'kolab_notes.editnote', 'kolab_notes.deletenotesconfirm', 'kolab_notes.entertitle', 'save', 'delete', 'cancel', 'close');
                 $this->include_script('notes_mail.js');
             }
         }
 
-        if (!$this->rc->output->ajax_call && !$this->rc->output->env['framed']) {
+        if (!$this->rc->output->ajax_call && !($this->rc->output->env['framed'] ?? null)) {
             $this->load_ui();
         }
 
         // get configuration for the Bonnie API
         $this->bonnie_api = libkolab::get_bonnie_api();
 
         // notes use fully encoded identifiers
         kolab_storage::$encode_ids = true;
     }
 
     /**
      * Hook into IMAP FETCH HEADER.FIELDS command and request MESSAGE-ID
      */
     public function storage_init($p)
     {
         $p['fetch_headers'] = trim($p['fetch_headers'] . ' MESSAGE-ID');
         return $p;
     }
 
     /**
      * Load and initialize UI class
      */
     private function load_ui()
     {
         if (!$this->ui) {
             require_once($this->home . '/kolab_notes_ui.php');
             $this->ui = new kolab_notes_ui($this);
             $this->ui->init();
         }
     }
 
     /**
      * Read available calendars for the current user and store them internally
      */
     private function _read_lists($force = false)
     {
         // already read sources
         if (isset($this->lists) && !$force)
             return $this->lists;
 
         // get all folders that have type "task"
         $folders = kolab_storage::sort_folders(kolab_storage::get_folders('note'));
         $this->lists = $this->folders = array();
 
         // find default folder
         $default_index = 0;
         foreach ($folders as $i => $folder) {
             if ($folder->default)
                 $default_index = $i;
         }
 
         // put default folder on top of the list
         if ($default_index > 0) {
             $default_folder = $folders[$default_index];
             unset($folders[$default_index]);
             array_unshift($folders, $default_folder);
         }
 
         foreach ($folders as $folder) {
             $item = $this->folder_props($folder);
             $this->lists[$item['id']] = $item;
             $this->folders[$item['id']] = $folder;
             $this->folders[$folder->name] = $folder;
         }
     }
 
     /**
      * Get a list of available folders from this source
      */
     public function get_lists(&$tree = null)
     {
         $this->_read_lists();
 
         // attempt to create a default folder for this user
         if (empty($this->lists)) {
             $folder = array('name' => 'Notes', 'type' => 'note', 'default' => true, 'subscribed' => true);
             if (kolab_storage::folder_update($folder)) {
                 $this->_read_lists(true);
             }
         }
 
         $folders = array();
         foreach ($this->lists as $id => $list) {
             if (!empty($this->folders[$id])) {
                 $folders[] = $this->folders[$id];
             }
         }
 
         // include virtual folders for a full folder tree
         if (!is_null($tree)) {
             $folders = kolab_storage::folder_hierarchy($folders, $tree);
         }
 
         $delim = $this->rc->get_storage()->get_hierarchy_delimiter();
 
         $lists = array();
         foreach ($folders as $folder) {
             $list_id = $folder->id;
             $imap_path = explode($delim, $folder->name);
 
             // find parent
             do {
               array_pop($imap_path);
               $parent_id = kolab_storage::folder_id(join($delim, $imap_path));
             }
             while (count($imap_path) > 1 && !$this->folders[$parent_id]);
 
             // restore "real" parent ID
             if ($parent_id && !$this->folders[$parent_id]) {
                 $parent_id = kolab_storage::folder_id($folder->get_parent());
             }
 
             $fullname = $folder->get_name();
             $listname = $folder->get_foldername();
 
             // special handling for virtual folders
             if ($folder instanceof kolab_storage_folder_user) {
                 $lists[$list_id] = array(
                     'id'       => $list_id,
                     'name'     => $fullname,
                     'listname' => $listname,
                     'title'    => $folder->get_title(),
                     'virtual'  => true,
                     'editable' => false,
                     'rights'   => 'l',
                     'group'    => 'other virtual',
                     'class'    => 'user',
                     'parent'   => $parent_id,
                 );
             }
             else if ($folder->virtual) {
                 $lists[$list_id] = array(
                     'id'       => $list_id,
                     'name'     => $fullname,
                     'listname' => $listname,
                     'virtual'  => true,
                     'editable' => false,
                     'rights'   => 'l',
                     'group'    => $folder->get_namespace(),
                     'parent'   => $parent_id,
                 );
             }
             else {
                 if (!$this->lists[$list_id]) {
                     $this->lists[$list_id] = $this->folder_props($folder);
                     $this->folders[$list_id] = $folder;
                 }
                 $this->lists[$list_id]['parent'] = $parent_id;
                 $lists[$list_id] = $this->lists[$list_id];
             }
         }
 
         return $lists;
     }
 
     /**
      * Search for shared or otherwise not listed folders the user has access
      *
      * @param string Search string
      * @param string Section/source to search
      * @return array List of notes folders
      */
     protected function search_lists($query, $source)
     {
         if (!kolab_storage::setup()) {
             return array();
         }
 
         $this->search_more_results = false;
         $this->lists = $this->folders = array();
 
         // find unsubscribed IMAP folders that have "event" type
         if ($source == 'folders') {
             foreach ((array)kolab_storage::search_folders('note', $query, array('other')) as $folder) {
                 $this->folders[$folder->id] = $folder;
                 $this->lists[$folder->id] = $this->folder_props($folder);
             }
         }
         // search other user's namespace via LDAP
         else if ($source == 'users') {
             $limit = $this->rc->config->get('autocomplete_max', 15) * 2;  // we have slightly more space, so display twice the number
             foreach (kolab_storage::search_users($query, 0, array(), $limit * 10) as $user) {
                 $folders = array();
                 // search for note folders shared by this user
                 foreach (kolab_storage::list_user_folders($user, 'note', false) as $foldername) {
                     $folders[] = new kolab_storage_folder($foldername, 'note');
                 }
 
                 if (count($folders)) {
                     $userfolder = new kolab_storage_folder_user($user['kolabtargetfolder'], '', $user);
                     $this->folders[$userfolder->id] = $userfolder;
                     $this->lists[$userfolder->id] = $this->folder_props($userfolder);
 
                     foreach ($folders as $folder) {
                         $this->folders[$folder->id] = $folder;
                         $this->lists[$folder->id] = $this->folder_props($folder);
                         $count++;
                     }
                 }
 
                 if ($count >= $limit) {
                     $this->search_more_results = true;
                     break;
                 }
             }
 
         }
 
         return $this->get_lists();
     }
 
     /**
      * Derive list properties from the given kolab_storage_folder object
      */
     protected function folder_props($folder)
     {
         if ($folder->get_namespace() == 'personal') {
             $norename = false;
             $editable = true;
             $rights = 'lrswikxtea';
             $alarms = true;
         }
         else {
             $alarms = false;
             $rights = 'lr';
             $editable = false;
             if (($myrights = $folder->get_myrights()) && !PEAR::isError($myrights)) {
                 $rights = $myrights;
                 if (strpos($rights, 't') !== false || strpos($rights, 'd') !== false)
                     $editable = strpos($rights, 'i');
             }
             $info = $folder->get_folder_info();
             $norename = $readonly || $info['norename'] || $info['protected'];
         }
 
         $list_id = $folder->id;
         return array(
             'id' => $list_id,
             'name' => $folder->get_name(),
             'listname' => $folder->get_foldername(),
             'editname' => $folder->get_foldername(),
             'editable' => $editable,
             'rights'   => $rights,
             'norename' => $norename,
             'parentfolder' => $folder->get_parent(),
             'subscribed' => (bool)$folder->is_subscribed(),
             'default'  => $folder->default,
             'group'    => $folder->default ? 'default' : $folder->get_namespace(),
             'class'    => trim($folder->get_namespace() . ($folder->default ? ' default' : '')),
         );
     }
 
     /**
      * Get the kolab_calendar instance for the given calendar ID
      *
      * @param string List identifier (encoded imap folder name)
      * @return object kolab_storage_folder Object nor null if list doesn't exist
      */
     public function get_folder($id)
     {
         // create list and folder instance if necesary
         if (!$this->lists[$id]) {
             $folder = kolab_storage::get_folder(kolab_storage::id_decode($id));
             if ($folder->type) {
                 $this->folders[$id] = $folder;
                 $this->lists[$id] = $this->folder_props($folder);
             }
         }
 
         return $this->folders[$id];
     }
 
     /*******  UI functions  ********/
 
     /**
      * Render main view of the tasklist task
      */
     public function notes_view()
     {
         $this->ui->init();
         $this->ui->init_templates();
         $this->rc->output->set_pagetitle($this->gettext('navtitle'));
         $this->rc->output->send('kolab_notes.notes');
     }
 
     /**
      * Deliver a rediced UI for inline (dialog)
      */
     public function dialog_view()
     {
         // resolve message reference
         if ($msgref = rcube_utils::get_input_value('_msg', rcube_utils::INPUT_GPC, true)) {
             $storage = $this->rc->get_storage();
             list($uid, $folder) = explode('-', $msgref, 2);
             if ($message = $storage->get_message_headers($msgref)) {
                 $this->rc->output->set_env('kolab_notes_template', array(
                     '_from_mail' => true,
                     'title' => $message->get('subject'),
                     'links' => array(kolab_storage_config::get_message_reference(
                         kolab_storage_config::get_message_uri($message, $folder),
                         'note'
                     )),
                 ));
             }
         }
 
         $this->ui->init_templates();
         $this->rc->output->send('kolab_notes.dialogview');
     }
 
     /**
      * Handler to retrieve note records for the given list and/or search query
      */
     public function notes_fetch()
     {
         $search = rcube_utils::get_input_value('_q', rcube_utils::INPUT_GPC, true);
         $list   = rcube_utils::get_input_value('_list', rcube_utils::INPUT_GPC);
 
         $data = $this->notes_data($this->list_notes($list, $search), $tags);
 
         $this->rc->output->command('plugin.data_ready', array(
                 'list'   => $list,
                 'search' => $search,
                 'data'   => $data,
                 'tags'   => array_values($tags)
         ));
     }
 
     /**
      * Convert the given note records for delivery to the client
      */
     protected function notes_data($records, &$tags)
     {
         $config = kolab_storage_config::get_instance();
         $tags   = $config->apply_tags($records);
         $config->apply_links($records);
 
         foreach ($records as $i => $rec) {
             unset($records[$i]['description']);
             $this->_client_encode($records[$i]);
         }
 
         return $records;
     }
 
     /**
      * Read note records for the given list from the storage backend
      */
     protected function list_notes($list_id, $search = null)
     {
         $results = array();
 
         // query Kolab storage
         $query = array();
 
         // full text search (only works with cache enabled)
         if (strlen($search)) {
             $words = array_filter(rcube_utils::normalize_string(mb_strtolower($search), true));
             foreach ($words as $word) {
                 if (strlen($word) > 2) {  // only words > 3 chars are stored in DB
                     $query[] = array('words', '~', $word);
                 }
             }
         }
 
         $this->_read_lists();
         if ($folder = $this->get_folder($list_id)) {
             foreach ($folder->select($query, empty($query)) as $record) {
                 // post-filter search results
                 if (strlen($search)) {
                     $matches = 0;
                     $contents = mb_strtolower(
                         $record['title'] .
                         ($this->is_html($record) ? strip_tags($record['description']) : $record['description'])
                     );
                     foreach ($words as $word) {
                         if (mb_strpos($contents, $word) !== false) {
                             $matches++;
                         }
                     }
 
                     // skip records not matching all search words
                     if ($matches < count($words)) {
                         continue;
                     }
                 }
                 $record['list'] = $list_id;
                 $results[] = $record;
             }
         }
 
         return $results;
     }
 
     /**
      * Handler for delivering a full note record to the client
      */
     public function note_record()
     {
         $data = $this->get_note(array(
             'uid'  => rcube_utils::get_input_value('_id', rcube_utils::INPUT_GPC),
             'list' => rcube_utils::get_input_value('_list', rcube_utils::INPUT_GPC),
         ));
 
         // encode for client use
         if (is_array($data)) {
             $this->_client_encode($data);
         }
 
         $this->rc->output->command('plugin.render_note', $data);
     }
 
     /**
      * Get the full note record identified by the given UID + Lolder identifier
      */
     public function get_note($note)
     {
         if (is_array($note)) {
             $uid = $note['uid'] ?: $note['id'];
             $list_id = $note['list'];
         }
         else {
             $uid = $note;
         }
 
         // deliver from in-memory cache
         $key = $list_id . ':' . $uid;
         if ($this->cache[$key]) {
             return $this->cache[$key];
         }
 
         $result = false;
 
         $this->_read_lists();
         if ($list_id) {
             if ($folder = $this->get_folder($list_id)) {
                 $result = $folder->get_object($uid);
             }
         }
         // iterate over all calendar folders and search for the event ID
         else {
             foreach ($this->folders as $list_id => $folder) {
                 if ($result = $folder->get_object($uid)) {
                     $result['list'] = $list_id;
                     break;
                 }
             }
         }
 
         if ($result) {
             // get note tags
             $result['tags'] = $this->get_tags($result['uid']);
             // get note links
             $result['links'] = $this->get_links($result['uid']);
         }
 
         return $result;
     }
 
     /**
      * Helper method to encode the given note record for use in the client
      */
     private function _client_encode(&$note)
     {
         foreach ($note as $key => $prop) {
             if ($key[0] == '_' || $key == 'x-custom') {
                 unset($note[$key]);
             }
         }
 
         foreach (array('created','changed') as $key) {
             if (is_object($note[$key]) && $note[$key] instanceof DateTime) {
                 $note[$key.'_'] = $note[$key]->format('U');
                 $note[$key] = $this->rc->format_date($note[$key]);
             }
         }
 
         // clean HTML contents
         if (!empty($note['description']) && $this->is_html($note)) {
             $note['html'] = $this->_wash_html($note['description']);
         }
 
         // convert link URIs references into structs
         if (array_key_exists('links', $note)) {
             foreach ((array)$note['links'] as $i => $link) {
                 if (strpos($link, 'imap://') === 0 && ($msgref = kolab_storage_config::get_message_reference($link, 'note'))) {
                     $note['links'][$i] = $msgref;
                 }
             }
         }
 
         return $note;
     }
 
     /**
      * Handler for client-initiated actions on a single note record
      */
     public function note_action()
     {
         $action = rcube_utils::get_input_value('_do', rcube_utils::INPUT_POST);
         $note   = rcube_utils::get_input_value('_data', rcube_utils::INPUT_POST, true);
 
         $success = $silent = false;
         switch ($action) {
             case 'new':
             case 'edit':
                 if ($success = $this->save_note($note)) {
                     $refresh = $this->get_note($note);
                 }
                 break;
 
             case 'move':
                 $uids = explode(',', $note['uid']);
                 foreach ($uids as $uid) {
                     $note['uid'] = $uid;
                     if (!($success = $this->move_note($note, $note['to']))) {
                         $refresh = $this->get_note($note);
                         break;
                     }
                 }
                 break;
 
             case 'delete':
                 $uids = explode(',', $note['uid']);
                 foreach ($uids as $uid) {
                     $note['uid'] = $uid;
                     if (!($success = $this->delete_note($note))) {
                         $refresh = $this->get_note($note);
                         break;
                     }
                 }
                 break;
 
             case 'changelog':
                 $data = $this->get_changelog($note);
                 if (is_array($data) && !empty($data)) {
                     $rcmail = $this->rc;
                     $dtformat = $rcmail->config->get('date_format') . ' ' . $this->rc->config->get('time_format');
                     array_walk($data, function(&$change) use ($lib, $rcmail, $dtformat) {
                       if ($change['date']) {
                           $dt = rcube_utils::anytodatetime($change['date']);
                           if ($dt instanceof DateTime) {
                               $change['date'] = $rcmail->format_date($dt, $dtformat);
                           }
                       }
                     });
                     $this->rc->output->command('plugin.note_render_changelog', $data);
                 }
                 else {
                     $this->rc->output->command('plugin.note_render_changelog', false);
                 }
                 $silent = true;
                 break;
 
             case 'diff':
                 $silent = true;
                 $data = $this->get_diff($note, $note['rev1'], $note['rev2']);
                 if (is_array($data)) {
                     $this->rc->output->command('plugin.note_show_diff', $data);
                 }
                 else {
                     $this->rc->output->command('display_message', $this->gettext('objectdiffnotavailable'), 'error');
                 }
                 break;
 
             case 'show':
                 if ($rec = $this->get_revison($note, $note['rev'])) {
                     $this->rc->output->command('plugin.note_show_revision', $this->_client_encode($rec));
                 }
                 else {
                     $this->rc->output->command('display_message', $this->gettext('objectnotfound'), 'error');
                 }
                 $silent = true;
                 break;
 
             case 'restore':
                 if ($this->restore_revision($note, $note['rev'])) {
                     $refresh = $this->get_note($note);
                     $this->rc->output->command('display_message', $this->gettext(array('name' => 'objectrestoresuccess', 'vars' => array('rev' => $note['rev']))), 'confirmation');
                     $this->rc->output->command('plugin.close_history_dialog');
                 }
                 else {
                     $this->rc->output->command('display_message', $this->gettext('objectrestoreerror'), 'error');
                 }
                 $silent = true;
                 break;
         }
 
         // show confirmation/error message
         if ($success) {
             $this->rc->output->show_message('successfullysaved', 'confirmation');
         }
         else if (!$silent) {
             $this->rc->output->show_message('errorsaving', 'error');
         }
 
         // unlock client
         $this->rc->output->command('plugin.unlock_saving');
 
         if ($refresh) {
             $this->rc->output->command('plugin.update_note', $this->_client_encode($refresh));
         }
     }
 
     /**
      * Update an note record with the given data
      *
      * @param array Hash array with note properties (id, list)
      * @return boolean True on success, False on error
      */
     private function save_note(&$note)
     {
         $this->_read_lists();
 
         $list_id = $note['list'];
         if (!$list_id || !($folder = $this->get_folder($list_id)))
             return false;
 
         // moved from another folder
         if ($note['_fromlist'] && ($fromfolder = $this->get_folder($note['_fromlist']))) {
             if (!$fromfolder->move($note['uid'], $folder->name))
                 return false;
 
             unset($note['_fromlist']);
         }
 
         // load previous version of this record to merge
         if ($note['uid']) {
             $old = $folder->get_object($note['uid']);
             if (!$old || PEAR::isError($old))
                 return false;
 
             // merge existing properties if the update isn't complete
             if (!isset($note['title']) || !isset($note['description']))
                 $note += $old;
         }
 
         // generate new note object from input
         $object = $this->_write_preprocess($note, $old);
 
         // email links and tags are handled separately
         $links = $object['links'];
         $tags  = $object['tags'];
 
         unset($object['links']);
         unset($object['tags']);
 
         $saved = $folder->save($object, 'note', $note['uid']);
 
         if (!$saved) {
             rcube::raise_error(array(
                 'code' => 600, 'type' => 'php',
                 'file' => __FILE__, 'line' => __LINE__,
                 'message' => "Error saving note object to Kolab server"),
                 true, false);
             $saved = false;
         }
         else {
             // save links in configuration.relation object
             $this->save_links($object['uid'], $links);
             // save tags in configuration.relation object
             $this->save_tags($object['uid'], $tags);
 
             $note         = $object;
             $note['list'] = $list_id;
             $note['tags'] = (array) $tags;
 
             // cache this in memory for later read
             $key = $list_id . ':' . $note['uid'];
             $this->cache[$key] = $note;
         }
 
         return $saved;
     }
 
     /**
      * Move the given note to another folder
      */
     function move_note($note, $list_id)
     {
         $this->_read_lists();
 
         $tofolder   = $this->get_folder($list_id);
         $fromfolder = $this->get_folder($note['list']);
 
         if ($fromfolder && $tofolder) {
             return $fromfolder->move($note['uid'], $tofolder->name);
         }
 
         return false;
     }
 
     /**
      * Remove a single note record from the backend
      *
      * @param array   Hash array with note properties (id, list)
      * @param boolean Remove record irreversible (mark as deleted otherwise)
      * @return boolean True on success, False on error
      */
     public function delete_note($note, $force = true)
     {
         $this->_read_lists();
 
         $list_id = $note['list'];
         if (!$list_id || !($folder = $this->get_folder($list_id))) {
             return false;
         }
 
         $status = $folder->delete($note['uid'], $force);
 
         if ($status) {
             $this->save_links($note['uid'], null);
             $this->save_tags($note['uid'], null);
         }
 
         return $status;
     }
 
     /**
      * Render the template for printing with placeholders
      */
     public function print_note()
     {
         $uid  = rcube_utils::get_input_value('_uid', rcube_utils::INPUT_GET);
         $list = rcube_utils::get_input_value('_list', rcube_utils::INPUT_GET);
 
         $this->note = $this->get_note(array('uid' => $uid, 'list' => $list));
 
         // encode for client use
         if (is_array($this->note)) {
             $this->_client_encode($this->note);
         }
 
         $this->rc->output->set_pagetitle($this->note['title']);
         $this->rc->output->add_handlers(array(
                 'noteheader' => array($this, 'print_note_header'),
                 'notebody'   => array($this, 'print_note_body'),
         ));
 
         $this->include_script('notes.js');
 
         $this->rc->output->send('kolab_notes.print');
     }
 
     public function print_note_header()
     {
         $tags = array_map(array('rcube', 'Q'), (array) $this->note['tags']);
         $tags = implode(' ', $tags);
 
         return html::tag('h1', array('id' => 'notetitle'), rcube::Q($this->note['title']))
             . html::div(array('id' => 'notetags', 'class' => 'tagline'), $tags)
             . html::div('dates',
                 html::label(null, rcube::Q($this->gettext('created')))
                 . html::span(array('id' => 'notecreated'), rcube::Q($this->note['created']))
                 . html::label(null, rcube::Q($this->gettext('changed')))
                 . html::span(array('id' => 'notechanged'), rcube::Q($this->note['changed']))
             );
     }
 
     public function print_note_body()
     {
         return isset($this->note['html']) ? $this->note['html'] : rcube::Q($this->note['description']);
     }
 
     /**
      * Provide a list of revisions for the given object
      *
      * @param array  $note Hash array with note properties
      * @return array List of changes, each as a hash array
      */
     public function get_changelog($note)
     {
         if (empty($this->bonnie_api)) {
             return false;
         }
 
         list($uid, $mailbox, $msguid) = $this->_resolve_note_identity($note);
 
         $result = $uid && $mailbox ? $this->bonnie_api->changelog('note', $uid, $mailbox, $msguid) : null;
         if (is_array($result) && $result['uid'] == $uid) {
             return $result['changes'];
         }
 
         return false;
     }
 
     /**
      * Return full data of a specific revision of a note record
      *
      * @param mixed  $note UID string or hash array with note properties
      * @param mixed  $rev Revision number
      *
      * @return array Note object as hash array
      */
     public function get_revison($note, $rev)
     {
         if (empty($this->bonnie_api)) {
             return false;
         }
 
         list($uid, $mailbox, $msguid) = $this->_resolve_note_identity($note);
 
         // call Bonnie API
         $result = $this->bonnie_api->get('note', $uid, $rev, $mailbox, $msguid);
         if (is_array($result) && $result['uid'] == $uid && !empty($result['xml'])) {
             $format = kolab_format::factory('note');
             $format->load($result['xml']);
             $rec = $format->to_array();
 
             if ($format->is_valid()) {
                 $rec['rev'] = $result['rev'];
                 return $rec;
             }
         }
 
         return false;
     }
 
     /**
      * Get a list of property changes beteen two revisions of a note object
      *
      * @param array  $$note Hash array with note properties
      * @param mixed  $rev   Revisions: "from:to"
      *
      * @return array List of property changes, each as a hash array
      */
     public function get_diff($note, $rev1, $rev2)
     {
         if (empty($this->bonnie_api)) {
             return false;
         }
 
         list($uid, $mailbox, $msguid) = $this->_resolve_note_identity($note);
 
         // call Bonnie API
         $result = $this->bonnie_api->diff('note', $uid, $rev1, $rev2, $mailbox, $msguid);
         if (is_array($result) && $result['uid'] == $uid) {
             $result['rev1'] = $rev1;
             $result['rev2'] = $rev2;
 
             // convert some properties, similar to self::_client_encode()
             $keymap = array(
                 'summary'  => 'title',
                 'lastmodified-date' => 'changed',
             );
 
             // map kolab object properties to keys and values the client expects
             array_walk($result['changes'], function(&$change, $i) use ($keymap) {
                 if (array_key_exists($change['property'], $keymap)) {
                     $change['property'] = $keymap[$change['property']];
                 }
 
                 if ($change['property'] == 'created' || $change['property'] == 'changed') {
                     if ($old_ = rcube_utils::anytodatetime($change['old'])) {
                         $change['old_'] = $this->rc->format_date($old_);
                     }
                     if ($new_ = rcube_utils::anytodatetime($change['new'])) {
                         $change['new_'] = $this->rc->format_date($new_);
                     }
                 }
 
                 // compute a nice diff of note contents
                 if ($change['property'] == 'description') {
                     $change['diff_'] = libkolab::html_diff($change['old'], $change['new']);
                     if (!empty($change['diff_'])) {
                         unset($change['old'], $change['new']);
                         $change['diff_'] = preg_replace(array('!^.*<body[^>]*>!Uims','!</body>.*$!Uims'), '', $change['diff_']);
                         $change['diff_'] = preg_replace("!</(p|li|span)>\n!", '</\\1>', $change['diff_']);
                     }
                 }
             });
 
             return $result;
         }
 
         return false;
     }
 
     /**
      * Command the backend to restore a certain revision of a note.
      * This shall replace the current object with an older version.
      *
      * @param array  $note Hash array with note properties (id, list)
      * @param mixed  $rev Revision number
      *
      * @return boolean True on success, False on failure
      */
     public function restore_revision($note, $rev)
     {
         if (empty($this->bonnie_api)) {
             return false;
         }
 
         list($uid, $mailbox, $msguid) = $this->_resolve_note_identity($note);
 
         $folder = $this->get_folder($note['list']);
         $success = false;
 
         if ($folder && ($raw_msg = $this->bonnie_api->rawdata('note', $uid, $rev, $mailbox))) {
             $imap = $this->rc->get_storage();
 
             // insert $raw_msg as new message
             if ($imap->save_message($folder->name, $raw_msg, null, false)) {
                 $success = true;
 
                 // delete old revision from imap and cache
                 $imap->delete_message($msguid, $folder->name);
                 $folder->cache->set($msguid, false);
                 $this->cache = array();
             }
         }
 
         return $success;
     }
 
     /**
      * Helper method to resolved the given note identifier into uid and mailbox
      *
      * @return array (uid,mailbox,msguid) tuple
      */
     private function _resolve_note_identity($note)
     {
         $mailbox = $msguid = null;
 
         if (!is_array($note)) {
             $note = $this->get_note($note);
         }
 
         if (is_array($note)) {
             $uid = $note['uid'] ?: $note['id'];
             $list = $note['list'];
         }
         else {
             return array(null, $mailbox, $msguid);
         }
 
         if ($folder = $this->get_folder($list)) {
             $mailbox = $folder->get_mailbox_id();
 
             // get object from storage in order to get the real object uid an msguid
             if ($rec = $folder->get_object($uid)) {
                 $msguid = $rec['_msguid'];
                 $uid = $rec['uid'];
             }
         }
 
         return array($uid, $mailbox, $msguid);
     }
 
 
     /**
      * Handler for client requests to list (aka folder) actions
      */
     public function list_action()
     {
         $action  = rcube_utils::get_input_value('_do', rcube_utils::INPUT_GPC);
         $list    = rcube_utils::get_input_value('_list', rcube_utils::INPUT_GPC, true);
         $success = $update_cmd = false;
 
         if (empty($action)) {
             $action = rcube_utils::get_input_value('action', rcube_utils::INPUT_GPC);
         }
 
         switch ($action) {
             case 'form-new':
             case 'form-edit':
                 $this->_read_lists();
                 $this->ui->list_editform($action, $this->lists[$list['id']], $this->folders[$list['id']]);
                 exit;
 
             case 'new':
                 $list['type'] = 'note';
                 $list['subscribed'] = true;
                 $folder = kolab_storage::folder_update($list);
 
                 if ($folder === false) {
                     $save_error = $this->gettext(kolab_storage::$last_error);
                 }
                 else {
                     $success = true;
                     $update_cmd = 'plugin.update_list';
                     $list['id'] = kolab_storage::folder_id($folder);
                     $list['_reload'] = true;
                 }
                 break;
 
             case 'edit':
                 $this->_read_lists();
                 $oldparent = $this->lists[$list['id']]['parentfolder'];
                 $newfolder = kolab_storage::folder_update($list);
 
                 if ($newfolder === false) {
                     $save_error = $this->gettext(kolab_storage::$last_error);
                 }
                 else {
                     $success = true;
                     $update_cmd = 'plugin.update_list';
                     $list['newid'] = kolab_storage::folder_id($newfolder);
                     $list['_reload'] = $list['parent'] != $oldparent;
 
                     // compose the new display name
                     $delim            = $this->rc->get_storage()->get_hierarchy_delimiter();
                     $path_imap        = explode($delim, $newfolder);
                     $list['name']     = kolab_storage::object_name($newfolder);
                     $list['editname'] = rcube_charset::convert(array_pop($path_imap), 'UTF7-IMAP');
                     $list['listname'] = $list['editname'];
                 }
                 break;
 
             case 'delete':
                 $this->_read_lists();
                 $folder = $this->get_folder($list['id']);
                 if ($folder && kolab_storage::folder_delete($folder->name)) {
                     $success = true;
                     $update_cmd = 'plugin.destroy_list';
                 }
                 else {
                     $save_error = $this->gettext(kolab_storage::$last_error);
                 }
                 break;
 
             case 'search':
                 $this->load_ui();
                 $results = array();
                 foreach ((array)$this->search_lists(rcube_utils::get_input_value('q', rcube_utils::INPUT_GPC), rcube_utils::get_input_value('source', rcube_utils::INPUT_GPC)) as $id => $prop) {
                     $editname = $prop['editname'];
                     unset($prop['editname']);  // force full name to be displayed
 
                     // let the UI generate HTML and CSS representation for this calendar
                     $html = $this->ui->folder_list_item($id, $prop, $jsenv, true);
                     $prop += (array)$jsenv[$id];
                     $prop['editname'] = $editname;
                     $prop['html'] = $html;
 
                     $results[] = $prop;
                 }
                 // report more results available
                 if ($this->driver->search_more_results) {
                     $this->rc->output->show_message('autocompletemore', 'notice');
                 }
 
                 $this->rc->output->command('multi_thread_http_response', $results, rcube_utils::get_input_value('_reqid', rcube_utils::INPUT_GPC));
                 return;
 
             case 'subscribe':
                 $success = false;
                 if ($list['id'] && ($folder = $this->get_folder($list['id']))) {
                     if (isset($list['permanent']))
                         $success |= $folder->subscribe(intval($list['permanent']));
                     if (isset($list['active']))
                         $success |= $folder->activate(intval($list['active']));
 
                     // apply to child folders, too
                     if ($list['recursive']) {
                         foreach ((array)kolab_storage::list_folders($folder->name, '*', 'node') as $subfolder) {
                             if (isset($list['permanent']))
                                 ($list['permanent'] ? kolab_storage::folder_subscribe($subfolder) : kolab_storage::folder_unsubscribe($subfolder));
                             if (isset($list['active']))
                                 ($list['active'] ? kolab_storage::folder_activate($subfolder) : kolab_storage::folder_deactivate($subfolder));
                         }
                     }
                 }
                 break;
         }
 
         $this->rc->output->command('plugin.unlock_saving');
 
         if ($success) {
             $this->rc->output->show_message('successfullysaved', 'confirmation');
 
             if ($update_cmd) {
                 $this->rc->output->command($update_cmd, $list);
             }
         }
         else {
             $error_msg = $this->gettext('errorsaving') . ($save_error ? ': ' . $save_error :'');
             $this->rc->output->show_message($error_msg, 'error');
         }
     }
 
     /**
      * Hook to add note attachments to message compose if the according parameter is present.
      * This completes the 'send note by mail' feature.
      */
     public function mail_message_compose($args)
     {
         if (!empty($args['param']['with_notes'])) {
             $uids = explode(',', $args['param']['with_notes']);
             $list = $args['param']['notes_list'];
 
             foreach ($uids as $uid) {
                 if ($note = $this->get_note(array('uid' => $uid, 'list' => $list))) {
                     $data = $this->note2message($note);
                     $args['attachments'][] = array(
                         'name'     => abbreviate_string($note['title'], 50, ''),
                         'mimetype' => 'message/rfc822',
                         'data'     => $data,
                         'size'     => strlen($data),
                     );
 
                     if (empty($args['param']['subject'])) {
                         $args['param']['subject'] = $note['title'];
                     }
                 }
             }
 
             unset($args['param']['with_notes'], $args['param']['notes_list']);
         }
 
         return $args;
     }
 
     /**
      * Lookup backend storage and find notes associated with the given message
      */
     public function mail_message_load($p)
     {
         if (!$p['object']->headers->others['x-kolab-type']) {
             $this->message_notes = $this->get_message_notes($p['object']->headers, $p['object']->folder);
         }
     }
 
     /**
      * Handler for 'messagebody_html' hook
      */
     public function mail_messagebody_html($args)
     {
         $html = '';
         foreach ($this->message_notes as $note) {
             $html .= html::a(array(
                 'href' => $this->rc->url(array('task' => 'notes', '_list' => $note['list'], '_id' => $note['uid'])),
                 'class' => 'kolabnotesref',
                 'rel' => $note['uid'] . '@' . $note['list'],
                 'target' => '_blank',
             ), rcube::Q($note['title']));
         }
 
         // prepend note links to message body
         if ($html) {
             $this->load_ui();
             $args['content'] = html::div('kolabmessagenotes boxinformation', $html) . $args['content'];
         }
 
         return $args;
     }
 
     /**
      * Determine whether the given note is HTML formatted
      */
     private function is_html($note)
     {
         // check for opening and closing <html> or <body> tags
         return (preg_match('/<(html|body)(\s+[a-z]|>)/', $note['description'], $m) && strpos($note['description'], '</'.$m[1].'>') > 0);
     }
 
     /**
      * Build an RFC 822 message from the given note
      */
     private function note2message($note)
     {
         $message = new Mail_mime("\r\n");
 
         $message->setParam('text_encoding', '8bit');
         $message->setParam('html_encoding', 'quoted-printable');
         $message->setParam('head_encoding', 'quoted-printable');
         $message->setParam('head_charset', RCUBE_CHARSET);
         $message->setParam('html_charset', RCUBE_CHARSET);
         $message->setParam('text_charset', RCUBE_CHARSET);
 
         $message->headers(array(
             'Subject' => $note['title'],
             'Date' => $note['changed']->format('r'),
         ));
 
         if ($this->is_html($note)) {
             $message->setHTMLBody($note['description']);
 
             // add a plain text version of the note content as an alternative part.
             $h2t = new rcube_html2text($note['description'], false, true, 0, RCUBE_CHARSET);
             $plain_part = rcube_mime::wordwrap($h2t->get_text(), $this->rc->config->get('line_length', 72), "\r\n", false, RCUBE_CHARSET);
             $plain_part = trim(wordwrap($plain_part, 998, "\r\n", true));
 
             // make sure all line endings are CRLF
             $plain_part = preg_replace('/\r?\n/', "\r\n", $plain_part);
 
             $message->setTXTBody($plain_part);
         }
         else {
             $message->setTXTBody($note['description']);
         }
 
         return $message->getMessage();
     }
 
     private function save_links($uid, $links)
     {
         $config = kolab_storage_config::get_instance();
         return $config->save_object_links($uid, (array) $links);
     }
 
     /**
      * Find messages assigned to specified note
      */
     private function get_links($uid)
     {
         $config = kolab_storage_config::get_instance();
         return $config->get_object_links($uid);
     }
 
     /**
      * Get note tags
      */
     private function get_tags($uid)
     {
         $config = kolab_storage_config::get_instance();
         $tags   = $config->get_tags($uid);
         $tags   = array_map(function($v) { return $v['name']; }, $tags);
 
         return $tags;
     }
 
     /**
      * Find notes assigned to specified message
      */
     private function get_message_notes($message, $folder)
     {
         $config = kolab_storage_config::get_instance();
         $result = $config->get_message_relations($message, $folder, 'note');
 
         foreach ($result as $idx => $note) {
             $result[$idx]['list'] = kolab_storage::folder_id($note['_mailbox']);
         }
 
         return $result;
     }
 
     /**
      * Update note tags
      */
     private function save_tags($uid, $tags)
     {
         $config = kolab_storage_config::get_instance();
         $config->save_tags($uid, $tags);
     }
 
     /**
      * Process the given note data (submitted by the client) before saving it
      */
     private function _write_preprocess($note, $old = array())
     {
         $object = $note;
 
         // TODO: handle attachments
 
         // convert link references into simple URIs
         if (array_key_exists('links', $note)) {
             $object['links'] = array_map(function($link){ return is_array($link) ? $link['uri'] : strval($link); }, $note['links']);
         }
         else {
             $object['links'] = $old['links'];
         }
 
         // clean up HTML content
         $object['description'] = $this->_wash_html($note['description']);
         $is_html = true;
 
         // try to be smart and convert to plain-text if no real formatting is detected
         if (preg_match('!<body><(?:p|pre)>(.*)</(?:p|pre)></body>!Uims', $object['description'], $m)) {
             if (!preg_match('!<(a|b|i|strong|em|p|span|div|pre|li|img)(\s+[a-z]|>)!im', $m[1], $n)
                 || ($n[1] != 'img' && !strpos($m[1], '</'.$n[1].'>'))
             ) {
                 // $converter = new rcube_html2text($m[1], false, true, 0);
                 // $object['description'] = rtrim($converter->get_text());
                 $object['description'] = html_entity_decode(preg_replace('!<br(\s+/)>!', "\n", $m[1]));
                 $is_html = false;
             }
         }
 
         // Add proper HTML header, otherwise Kontact renders it as plain text
         if ($is_html) {
             $object['description'] = '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN" "http://www.w3.org/TR/REC-html40/strict.dtd">'."\n" .
                 str_replace('<head>', '<head><meta name="qrichtext" content="1" />', $object['description']);
         }
 
         // copy meta data (starting with _) from old object
         foreach ((array)$old as $key => $val) {
             if (!isset($object[$key]) && $key[0] == '_')
                 $object[$key] = $val;
         }
 
         // make list of categories unique
         if (is_array($object['tags'])) {
             $object['tags'] = array_unique(array_filter($object['tags']));
         }
 
         unset($object['list'], $object['tempid'], $object['created'], $object['changed'], $object['created_'], $object['changed_']);
         return $object;
     }
 
     /**
      * Sanity checks/cleanups HTML content
      */
     private function _wash_html($html)
     {
         // Add header with charset spec., washtml cannot work without that
         $html = '<html><head>'
             . '<meta http-equiv="Content-Type" content="text/html; charset='.RCUBE_CHARSET.'" />'
             . '</head><body>' . $html . '</body></html>';
 
         // clean HTML with washtml by Frederic Motte
         $wash_opts = array(
             'show_washed'   => false,
             'allow_remote'  => 1,
             'charset'       => RCUBE_CHARSET,
             'html_elements' => array('html', 'head', 'meta', 'body', 'link'),
             'html_attribs'  => array('rel', 'type', 'name', 'http-equiv'),
         );
 
         // initialize HTML washer
         $washer = new rcube_washtml($wash_opts);
 
         $washer->add_callback('form', array($this, '_washtml_callback'));
         $washer->add_callback('a',    array($this, '_washtml_callback'));
 
         // Remove non-UTF8 characters
         $html = rcube_charset::clean($html);
 
         $html = $washer->wash($html);
 
         // remove unwanted comments (produced by washtml)
         $html = preg_replace('/<!--[^>]+-->/', '', $html);
 
         return $html;
     }
 
     /**
      * Callback function for washtml cleaning class
      */
     public function _washtml_callback($tagname, $attrib, $content, $washtml)
     {
         switch ($tagname) {
         case 'form':
             $out = html::div('form', $content);
             break;
 
         case 'a':
             // strip temporary link tags from plain-text markup
             $attrib = html::parse_attrib_string($attrib);
             if (!empty($attrib['class']) && strpos($attrib['class'], 'x-templink') !== false) {
                 // remove link entirely
                 if (strpos($attrib['href'], html_entity_decode($content)) !== false) {
                     $out = $content;
                     break;
                 }
                 $attrib['class'] = trim(str_replace('x-templink', '', $attrib['class']));
             }
             $out = html::a($attrib, $content);
             break;
 
         default:
             $out = '';
         }
 
         return $out;
     }
 
 }
diff --git a/plugins/libkolab/lib/kolab_storage.php b/plugins/libkolab/lib/kolab_storage.php
index 6d9db480..769eab6e 100644
--- a/plugins/libkolab/lib/kolab_storage.php
+++ b/plugins/libkolab/lib/kolab_storage.php
@@ -1,1810 +1,1811 @@
 <?php
 
 /**
  * Kolab storage class providing static methods to access groupware objects on a Kolab server.
  *
  * @version @package_version@
  * @author Thomas Bruederli <bruederli@kolabsys.com>
  * @author Aleksander Machniak <machniak@kolabsys.com>
  *
  * Copyright (C) 2012-2014, Kolab Systems AG <contact@kolabsys.com>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
  * published by the Free Software Foundation, either version 3 of the
  * License, or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU Affero General Public License for more details.
  *
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
 class kolab_storage
 {
     const CTYPE_KEY         = '/shared/vendor/kolab/folder-type';
     const CTYPE_KEY_PRIVATE = '/private/vendor/kolab/folder-type';
     const COLOR_KEY_SHARED  = '/shared/vendor/kolab/color';
     const COLOR_KEY_PRIVATE = '/private/vendor/kolab/color';
     const NAME_KEY_SHARED   = '/shared/vendor/kolab/displayname';
     const NAME_KEY_PRIVATE  = '/private/vendor/kolab/displayname';
     const UID_KEY_SHARED    = '/shared/vendor/kolab/uniqueid';
     const UID_KEY_CYRUS     = '/shared/vendor/cmu/cyrus-imapd/uniqueid';
 
     const ERROR_IMAP_CONN      = 1;
     const ERROR_CACHE_DB       = 2;
     const ERROR_NO_PERMISSION  = 3;
     const ERROR_INVALID_FOLDER = 4;
 
     public static $version = '3.0';
     public static $last_error;
     public static $encode_ids = false;
 
     private static $ready = false;
     private static $with_tempsubs = true;
     private static $subscriptions;
     private static $ldapcache = array();
     private static $ldap = array();
     private static $states;
     private static $config;
     private static $imap;
 
 
     // Default folder names
     private static $default_folders = array(
         'event'         => 'Calendar',
         'contact'       => 'Contacts',
         'task'          => 'Tasks',
         'note'          => 'Notes',
         'file'          => 'Files',
         'configuration' => 'Configuration',
         'journal'       => 'Journal',
         'mail.inbox'       => 'INBOX',
         'mail.drafts'      => 'Drafts',
         'mail.sentitems'   => 'Sent',
         'mail.wastebasket' => 'Trash',
         'mail.outbox'      => 'Outbox',
         'mail.junkemail'   => 'Junk',
     );
 
 
     /**
      * Setup the environment needed by the libs
      */
     public static function setup()
     {
         if (self::$ready)
             return true;
 
         $rcmail = rcube::get_instance();
         self::$config  = $rcmail->config;
         self::$version = strval($rcmail->config->get('kolab_format_version', self::$version));
         self::$imap    = $rcmail->get_storage();
         self::$ready   = class_exists('kolabformat') &&
             (self::$imap->get_capability('METADATA') || self::$imap->get_capability('ANNOTATEMORE') || self::$imap->get_capability('ANNOTATEMORE2'));
 
         if (self::$ready) {
             // do nothing
         }
         else if (!class_exists('kolabformat')) {
             rcube::raise_error(array(
                 'code' => 900, 'type' => 'php',
                 'message' => "required kolabformat module not found"
             ), true);
         }
         else if (self::$imap->get_error_code()) {
             rcube::raise_error(array(
                 'code' => 900, 'type' => 'php', 'message' => "IMAP error"
             ), true);
         }
 
         // adjust some configurable settings
         if ($event_scheduling_prop = $rcmail->config->get('kolab_event_scheduling_properties', null)) {
             kolab_format_event::$scheduling_properties = (array)$event_scheduling_prop;
         }
         // adjust some configurable settings
         if ($task_scheduling_prop = $rcmail->config->get('kolab_task_scheduling_properties', null)) {
             kolab_format_task::$scheduling_properties = (array)$task_scheduling_prop;
         }
 
         return self::$ready;
     }
 
     /**
      * Initializes LDAP object to resolve Kolab users
      *
      * @param string $name Name of the configuration option with LDAP config
      */
     public static function ldap($name = 'kolab_users_directory')
     {
         self::setup();
 
         $config = self::$config->get($name);
 
         if (empty($config)) {
             $name   = 'kolab_auth_addressbook';
             $config = self::$config->get($name);
         }
 
         if (self::$ldap[$name]) {
             return self::$ldap[$name];
         }
 
         if (!is_array($config)) {
             $ldap_config = (array)self::$config->get('ldap_public');
             $config = $ldap_config[$config];
         }
 
         if (empty($config)) {
             return null;
         }
 
         $ldap = new kolab_ldap($config);
 
         // overwrite filter option
         if ($filter = self::$config->get('kolab_users_filter')) {
             self::$config->set('kolab_auth_filter', $filter);
         }
 
         $user_field = $user_attrib = self::$config->get('kolab_users_id_attrib');
 
         // Fallback to kolab_auth_login, which is not attribute, but field name
         if (!$user_field && ($user_field = self::$config->get('kolab_auth_login', 'email'))) {
             $user_attrib = $config['fieldmap'][$user_field];
         }
 
         if ($user_field && $user_attrib) {
             $ldap->extend_fieldmap(array($user_field => $user_attrib));
         }
 
         self::$ldap[$name] = $ldap;
 
         return $ldap;
     }
 
     /**
      * Get a list of storage folders for the given data type
      *
      * @param string Data type to list folders for (contact,distribution-list,event,task,note)
      * @param boolean Enable to return subscribed folders only (null to use configured subscription mode)
      *
      * @return array List of Kolab_Folder objects (folder names in UTF7-IMAP)
      */
     public static function get_folders($type, $subscribed = null)
     {
         $folders = $folderdata = array();
 
         if (self::setup()) {
             foreach ((array)self::list_folders('', '*', $type, $subscribed, $folderdata) as $foldername) {
                 $folders[$foldername] = new kolab_storage_folder($foldername, $type, $folderdata[$foldername]);
             }
         }
 
         return $folders;
     }
 
     /**
      * Getter for the storage folder for the given type
      *
      * @param string Data type to list folders for (contact,distribution-list,event,task,note)
      * @return object kolab_storage_folder  The folder object
      */
     public static function get_default_folder($type)
     {
         if (self::setup()) {
             foreach ((array)self::list_folders('', '*', $type . '.default', false, $folderdata) as $foldername) {
                 return new kolab_storage_folder($foldername, $type, $folderdata[$foldername]);
             }
         }
 
         return null;
     }
 
     /**
      * Getter for a specific storage folder
      *
      * @param string IMAP folder to access (UTF7-IMAP)
      * @param string Expected folder type
      *
      * @return object kolab_storage_folder  The folder object
      */
     public static function get_folder($folder, $type = null)
     {
         return self::setup() ? new kolab_storage_folder($folder, $type) : null;
     }
 
     /**
      * Getter for a single Kolab object, identified by its UID.
      * This will search all folders storing objects of the given type.
      *
      * @param string Object UID
      * @param string Object type (contact,event,task,journal,file,note,configuration)
      * @return array The Kolab object represented as hash array or false if not found
      */
     public static function get_object($uid, $type)
     {
         self::setup();
         $folder = null;
         foreach ((array)self::list_folders('', '*', $type, null, $folderdata) as $foldername) {
             if (!$folder)
                 $folder = new kolab_storage_folder($foldername, $type, $folderdata[$foldername]);
             else
                 $folder->set_folder($foldername, $type, $folderdata[$foldername]);
 
             if ($object = $folder->get_object($uid))
                 return $object;
         }
 
         return false;
     }
 
     /**
      * Execute cross-folder searches with the given query.
      *
      * @param array  Pseudo-SQL query as list of filter parameter triplets
      * @param string Folder type (contact,event,task,journal,file,note,configuration)
      * @param int    Expected number of records or limit (for performance reasons)
      *
      * @return array List of Kolab data objects (each represented as hash array)
      * @see kolab_storage_format::select()
      */
     public static function select($query, $type, $limit = null)
     {
         self::setup();
         $folder = null;
         $result = array();
 
         foreach ((array)self::list_folders('', '*', $type, null, $folderdata) as $foldername) {
             $folder = new kolab_storage_folder($foldername, $type, $folderdata[$foldername]);
 
             if ($limit) {
                 $folder->set_order_and_limit(null, $limit);
             }
 
             foreach ($folder->select($query) as $object) {
                 $result[] = $object;
             }
         }
 
         return $result;
     }
 
     /**
      * Returns Free-busy server URL
      */
     public static function get_freebusy_server()
     {
         $rcmail = rcube::get_instance();
 
         $url = 'https://' . $_SESSION['imap_host'] . '/freebusy';
         $url = $rcmail->config->get('kolab_freebusy_server', $url);
         $url = rcube_utils::resolve_url($url);
 
         return unslashify($url);
     }
 
     /**
      * Compose an URL to query the free/busy status for the given user
      *
      * @param string Email address of the user to get free/busy data for
      * @param object DateTime Start of the query range (optional)
      * @param object DateTime End of the query range (optional)
      *
      * @return string Fully qualified URL to query free/busy data
      */
     public static function get_freebusy_url($email, $start = null, $end = null)
     {
         $query = '';
         $param = array();
         $utc = new \DateTimeZone('UTC');
 
         // https://www.calconnect.org/pubdocs/CD0903%20Freebusy%20Read%20URL.pdf
 
         if ($start instanceof \DateTime) {
             $start->setTimezone($utc);
             $param['start'] = $param['dtstart'] = $start->format('Ymd\THis\Z');
         }
 
         if ($end instanceof \DateTime) {
             $end->setTimezone($utc);
             $param['end'] = $param['dtend'] = $end->format('Ymd\THis\Z');
         }
 
         if (!empty($param)) {
             $query = '?' . http_build_query($param);
         }
 
         $url = self::get_freebusy_server();
 
         if (strpos($url, '%u')) {
             // Expected configured full URL, just replace the %u variable
             // Note: Cyrus v3 Free-Busy service does not use .ifb extension
             $url = str_replace('%u', rawurlencode($email), $url);
         }
         else {
             $url .= '/' . $email . '.ifb';
         }
 
         return $url . $query;
     }
 
     /**
      * Creates folder ID from folder name
      *
      * @param string  $folder Folder name (UTF7-IMAP)
      * @param boolean $enc    Use lossless encoding
      * @return string Folder ID string
      */
     public static function folder_id($folder, $enc = null)
     {
         return $enc == true || ($enc === null && self::$encode_ids) ?
             self::id_encode($folder) :
             asciiwords(strtr($folder, '/.-', '___'));
     }
 
     /**
      * Encode the given ID to a safe ascii representation
      *
      * @param string $id Arbitrary identifier string
      *
      * @return string Ascii representation
      */
     public static function id_encode($id)
     {
         return rtrim(strtr(base64_encode($id), '+/', '-_'), '=');
     }
 
     /**
      * Convert the given identifier back to it's raw value
      *
      * @param string $id Ascii identifier
      * @return string Raw identifier string
      */
     public static function id_decode($id)
     {
       return base64_decode(str_pad(strtr($id, '-_', '+/'), strlen($id) % 4, '=', STR_PAD_RIGHT));
     }
 
     /**
      * Return the (first) path of the requested IMAP namespace
      *
      * @param string  Namespace name (personal, shared, other)
      * @return string IMAP root path for that namespace
      */
     public static function namespace_root($name)
     {
         self::setup();
 
         foreach ((array)self::$imap->get_namespace($name) as $paths) {
             if (strlen($paths[0]) > 1) {
                 return $paths[0];
             }
         }
 
         return '';
     }
 
     /**
      * Deletes IMAP folder
      *
      * @param string $name Folder name (UTF7-IMAP)
      *
      * @return bool True on success, false on failure
      */
     public static function folder_delete($name)
     {
         // clear cached entries first
         if ($folder = self::get_folder($name))
             $folder->cache->purge();
 
         $rcmail = rcube::get_instance();
         $plugin = $rcmail->plugins->exec_hook('folder_delete', array('name' => $name));
 
         $success = self::$imap->delete_folder($name);
         self::$last_error = self::$imap->get_error_str();
 
         return $success;
     }
 
     /**
      * Creates IMAP folder
      *
      * @param string $name       Folder name (UTF7-IMAP)
      * @param string $type       Folder type
      * @param bool   $subscribed Sets folder subscription
      * @param bool   $active     Sets folder state (client-side subscription)
      *
      * @return bool True on success, false on failure
      */
     public static function folder_create($name, $type = null, $subscribed = false, $active = false)
     {
         self::setup();
 
         $rcmail = rcube::get_instance();
         $plugin = $rcmail->plugins->exec_hook('folder_create', array('record' => array(
             'name' => $name,
             'subscribe' => $subscribed,
         )));
 
         if ($saved = self::$imap->create_folder($name, $subscribed)) {
             // set metadata for folder type
             if ($type) {
                 $saved = self::set_folder_type($name, $type);
 
                 // revert if metadata could not be set
                 if (!$saved) {
                     self::$imap->delete_folder($name);
                 }
                 // activate folder
                 else if ($active) {
                     self::set_state($name, true);
                 }
             }
         }
 
         if ($saved) {
             return true;
         }
 
         self::$last_error = self::$imap->get_error_str();
         return false;
     }
 
     /**
      * Renames IMAP folder
      *
      * @param string $oldname Old folder name (UTF7-IMAP)
      * @param string $newname New folder name (UTF7-IMAP)
      *
      * @return bool True on success, false on failure
      */
     public static function folder_rename($oldname, $newname)
     {
         self::setup();
 
         $rcmail = rcube::get_instance();
         $plugin = $rcmail->plugins->exec_hook('folder_rename', array(
             'oldname' => $oldname, 'newname' => $newname));
 
         $oldfolder = self::get_folder($oldname);
         $active    = self::folder_is_active($oldname);
         $success   = self::$imap->rename_folder($oldname, $newname);
         self::$last_error = self::$imap->get_error_str();
 
         // pass active state to new folder name
         if ($success && $active) {
             self::set_state($oldname, false);
             self::set_state($newname, true);
         }
 
         // assign existing cache entries to new resource uri
         if ($success && $oldfolder) {
             $oldfolder->cache->rename($newname);
         }
 
         return $success;
     }
 
     /**
      * Rename or Create a new IMAP folder.
      *
      * Does additional checks for permissions and folder name restrictions
      *
      * @param array &$prop Hash array with folder properties and metadata
      *  - name:       Folder name
      *  - oldname:    Old folder name when changed
      *  - parent:     Parent folder to create the new one in
      *  - type:       Folder type to create
      *  - subscribed: Subscribed flag (IMAP subscription)
      *  - active:     Activation flag (client-side subscription)
      *
      * @return string|false New folder name or False on failure
      *
      * @see self::set_folder_props() for list of other properties
      */
     public static function folder_update(&$prop)
     {
         self::setup();
 
         $folder    = rcube_charset::convert($prop['name'], RCUBE_CHARSET, 'UTF7-IMAP');
         $oldfolder = $prop['oldname']; // UTF7
         $parent    = $prop['parent']; // UTF7
         $delimiter = self::$imap->get_hierarchy_delimiter();
 
         if (strlen($oldfolder)) {
             $options = self::$imap->folder_info($oldfolder);
         }
 
         if (!empty($options) && ($options['norename'] || $options['protected'])) {
         }
         // sanity checks (from steps/settings/save_folder.inc)
         else if (!strlen($folder)) {
             self::$last_error = 'cannotbeempty';
             return false;
         }
         else if (strlen($folder) > 128) {
             self::$last_error = 'nametoolong';
             return false;
         }
         else {
             // these characters are problematic e.g. when used in LIST/LSUB
             foreach (array($delimiter, '%', '*') as $char) {
                 if (strpos($folder, $char) !== false) {
                     self::$last_error = 'forbiddencharacter';
                     return false;
                 }
             }
         }
 
         if (!empty($options) && ($options['protected'] || $options['norename'])) {
             $folder = $oldfolder;
         }
         else if (strlen($parent)) {
             $folder = $parent . $delimiter . $folder;
         }
         else {
             // add namespace prefix (when needed)
             $folder = self::$imap->mod_folder($folder, 'in');
         }
 
         // Check access rights to the parent folder
         if (strlen($parent) && (!strlen($oldfolder) || $oldfolder != $folder)) {
             $parent_opts = self::$imap->folder_info($parent);
             if ($parent_opts['namespace'] != 'personal'
                 && (empty($parent_opts['rights']) || !preg_match('/[ck]/', implode($parent_opts['rights'])))
             ) {
                 self::$last_error = 'No permission to create folder';
                 return false;
             }
         }
 
         // update the folder name
         if (strlen($oldfolder)) {
             if ($oldfolder != $folder) {
                 $result = self::folder_rename($oldfolder, $folder);
             }
             else {
                 $result = true;
             }
         }
         // create new folder
         else {
             $result = self::folder_create($folder, $prop['type'], $prop['subscribed'], $prop['active']);
         }
 
         if ($result) {
             self::set_folder_props($folder, $prop);
         }
 
         return $result ? $folder : false;
     }
 
     /**
      * Getter for human-readable name of Kolab object (folder)
      * with kolab_custom_display_names support.
      * See http://wiki.kolab.org/UI-Concepts/Folder-Listing for reference
      *
      * @param string $folder    IMAP folder name (UTF7-IMAP)
      * @param string $folder_ns Will be set to namespace name of the folder
      *
      * @return string Name of the folder-object
      */
     public static function object_name($folder, &$folder_ns=null)
     {
         // find custom display name in folder METADATA
         if ($name = self::custom_displayname($folder)) {
             return $name;
         }
 
         return self::object_prettyname($folder, $folder_ns);
     }
 
     /**
      * Get custom display name (saved in metadata) for the given folder
      */
     public static function custom_displayname($folder)
     {
         static $_metadata;
 
         // find custom display name in folder METADATA
         if (self::$config->get('kolab_custom_display_names', true) && self::setup()) {
             if ($_metadata !== null) {
                 $metadata = $_metadata;
             }
             else {
                 // For performance reasons ask for all folders, it will be cached as one cache entry
                 $metadata = self::$imap->get_metadata("*", array(self::NAME_KEY_PRIVATE, self::NAME_KEY_SHARED));
 
                 // If cache is disabled store result in memory
                 if (!self::$config->get('imap_cache')) {
                     $_metadata = $metadata;
                 }
             }
 
-            if ($data = $metadata[$folder]) {
+            if ($data = $metadata[$folder] ?? null) {
                 if (($name = $data[self::NAME_KEY_PRIVATE]) || ($name = $data[self::NAME_KEY_SHARED])) {
                     return $name;
                 }
             }
         }
 
         return false;
     }
 
     /**
      * Getter for human-readable name of Kolab object (folder)
      * See http://wiki.kolab.org/UI-Concepts/Folder-Listing for reference
      *
      * @param string $folder    IMAP folder name (UTF7-IMAP)
      * @param string $folder_ns Will be set to namespace name of the folder
      *
      * @return string Name of the folder-object
      */
     public static function object_prettyname($folder, &$folder_ns=null)
     {
         self::setup();
 
         $found     = false;
         $namespace = self::$imap->get_namespace();
+        $prefix = null;
 
         if (!empty($namespace['shared'])) {
             foreach ($namespace['shared'] as $ns) {
                 if (strlen($ns[0]) && strpos($folder, $ns[0]) === 0) {
                     $prefix = '';
                     $folder = substr($folder, strlen($ns[0]));
                     $delim  = $ns[1];
                     $found  = true;
                     $folder_ns = 'shared';
                     break;
                 }
             }
         }
 
         if (!$found && !empty($namespace['other'])) {
             foreach ($namespace['other'] as $ns) {
                 if (strlen($ns[0]) && strpos($folder, $ns[0]) === 0) {
                     // remove namespace prefix and extract username
                     $folder = substr($folder, strlen($ns[0]));
                     $delim  = $ns[1];
 
                     // get username part and map it to user name
                     $pos = strpos($folder, $delim);
                     $fid = $pos ? substr($folder, 0, $pos) : $folder;
 
                     if ($user = self::folder_id2user($fid, true)) {
                         $fid = str_replace($delim, '', $user);
                     }
 
                     $prefix = "($fid)";
                     $folder = $pos ? substr($folder, $pos + 1) : '';
                     $found  = true;
                     $folder_ns = 'other';
                     break;
                 }
             }
         }
 
         if (!$found && !empty($namespace['personal'])) {
             foreach ($namespace['personal'] as $ns) {
                 if (strlen($ns[0]) && strpos($folder, $ns[0]) === 0) {
                     // remove namespace prefix
                     $folder = substr($folder, strlen($ns[0]));
                     $prefix = '';
                     $delim  = $ns[1];
                     $found  = true;
                     break;
                 }
             }
         }
 
         if (empty($delim))
             $delim = self::$imap->get_hierarchy_delimiter();
 
         $folder = rcube_charset::convert($folder, 'UTF7-IMAP');
         $folder = html::quote($folder);
         $folder = str_replace(html::quote($delim), ' &raquo; ', $folder);
 
         if ($prefix)
             $folder = html::quote($prefix) . ($folder !== '' ? ' ' . $folder : '');
 
         if (!$folder_ns)
             $folder_ns = 'personal';
 
         return $folder;
     }
 
     /**
      * Helper method to generate a truncated folder name to display.
      * Note: $origname is a string returned by self::object_name()
      */
     public static function folder_displayname($origname, &$names)
     {
         $name = $origname;
 
         // find folder prefix to truncate
         for ($i = count($names)-1; $i >= 0; $i--) {
             if (strpos($name, $names[$i] . ' &raquo; ') === 0) {
                 $length = strlen($names[$i] . ' &raquo; ');
                 $prefix = substr($name, 0, $length);
                 $count  = count(explode(' &raquo; ', $prefix));
                 $diff   = 1;
 
                 // check if prefix folder is in other users namespace
                 for ($n = count($names)-1; $n >= 0; $n--) {
                     if (strpos($prefix, '(' . $names[$n] . ') ') === 0) {
                         $diff = 0;
                         break;
                     }
                 }
 
                 $name = str_repeat('&nbsp;&nbsp;&nbsp;', $count - $diff) . '&raquo; ' . substr($name, $length);
                 break;
             }
             // other users namespace and parent folder exists
             else if (strpos($name, '(' . $names[$i] . ') ') === 0) {
                 $length = strlen('(' . $names[$i] . ') ');
                 $prefix = substr($name, 0, $length);
                 $count  = count(explode(' &raquo; ', $prefix));
                 $name   = str_repeat('&nbsp;&nbsp;&nbsp;', $count) . '&raquo; ' . substr($name, $length);
                 break;
             }
         }
 
         $names[] = $origname;
 
         return $name;
     }
 
     /**
      * Creates a SELECT field with folders list
      *
      * @param string $type    Folder type
      * @param array  $attrs   SELECT field attributes (e.g. name)
      * @param string $current The name of current folder (to skip it)
      *
      * @return html_select SELECT object
      */
     public static function folder_selector($type, $attrs, $current = '')
     {
         // get all folders of specified type (sorted)
         $folders = self::get_folders($type, true);
 
         $delim = self::$imap->get_hierarchy_delimiter();
         $names = array();
         $len   = strlen($current);
 
         if ($len && ($rpos = strrpos($current, $delim))) {
             $parent = substr($current, 0, $rpos);
             $p_len  = strlen($parent);
         }
 
         // Filter folders list
         foreach ($folders as $c_folder) {
             $name = $c_folder->name;
 
             // skip current folder and it's subfolders
             if ($len) {
                 if ($name == $current) {
                     // Make sure parent folder is listed (might be skipped e.g. if it's namespace root)
                     if ($p_len && !isset($names[$parent])) {
                         $names[$parent] = self::object_name($parent);
                     }
                     continue;
                 }
                 if (strpos($name, $current.$delim) === 0) {
                     continue;
                 }
             }
 
             // always show the parent of current folder
             if ($p_len && $name == $parent) {
             }
             // skip folders where user have no rights to create subfolders
             else if ($c_folder->get_owner() != $_SESSION['username']) {
                 $rights = $c_folder->get_myrights();
                 if (!preg_match('/[ck]/', $rights)) {
                     continue;
                 }
             }
 
             $names[$name] = $c_folder->get_name();
         }
 
         // Build SELECT field of parent folder
         $attrs['is_escaped'] = true;
         $select = new html_select($attrs);
         $select->add('---', '');
 
         $listnames = array();
         foreach (array_keys($names) as $imap_name) {
             $name = $origname = $names[$imap_name];
 
             // find folder prefix to truncate
             for ($i = count($listnames)-1; $i >= 0; $i--) {
                 if (strpos($name, $listnames[$i].' &raquo; ') === 0) {
                     $length = strlen($listnames[$i].' &raquo; ');
                     $prefix = substr($name, 0, $length);
                     $count  = count(explode(' &raquo; ', $prefix));
                     $name   = str_repeat('&nbsp;&nbsp;', $count-1) . '&raquo; ' . substr($name, $length);
                     break;
                 }
             }
 
             $listnames[] = $origname;
             $select->add($name, $imap_name);
         }
 
         return $select;
     }
 
     /**
      * Returns a list of folder names
      *
      * @param string  Optional root folder
      * @param string  Optional name pattern
      * @param string  Data type to list folders for (contact,event,task,journal,file,note,mail,configuration)
      * @param boolean Enable to return subscribed folders only (null to use configured subscription mode)
      * @param array   Will be filled with folder-types data
      *
      * @return array List of folders
      */
     public static function list_folders($root = '', $mbox = '*', $filter = null, $subscribed = null, &$folderdata = array())
     {
         if (!self::setup()) {
             return null;
         }
 
         // use IMAP subscriptions
         if ($subscribed === null && self::$config->get('kolab_use_subscriptions')) {
             $subscribed = true;
         }
 
         if (!$filter) {
             // Get ALL folders list, standard way
             if ($subscribed) {
                 $folders = self::_imap_list_subscribed($root, $mbox, $filter);
             }
             else {
                 $folders = self::_imap_list_folders($root, $mbox);
             }
 
             return $folders;
         }
         $prefix = $root . $mbox;
         $regexp = '/^' . preg_quote($filter, '/') . '(\..+)?$/';
 
         // get folders types for all folders
         $folderdata = self::folders_typedata($prefix);
 
         if (!is_array($folderdata)) {
             return array();
         }
 
         // If we only want groupware folders and don't care about the subscription state,
         // then the metadata will already contain all folder names and we can avoid the LIST below.
         if (!$subscribed && $filter != 'mail' && $prefix == '*') {
             foreach ($folderdata as $folder => $type) {
                 if (!preg_match($regexp, $type)) {
                     unset($folderdata[$folder]);
                 }
             }
 
             return self::$imap->sort_folder_list(array_keys($folderdata), true);
         }
 
         // Get folders list
         if ($subscribed) {
             $folders = self::_imap_list_subscribed($root, $mbox, $filter);
         }
         else {
             $folders = self::_imap_list_folders($root, $mbox);
         }
 
         // In case of an error, return empty list (?)
         if (!is_array($folders)) {
             return array();
         }
 
         // Filter folders list
         foreach ($folders as $idx => $folder) {
-            $type = $folderdata[$folder];
+            $type = $folderdata[$folder] ?? null;
 
             if ($filter == 'mail' && empty($type)) {
                 continue;
             }
             if (empty($type) || !preg_match($regexp, $type)) {
                 unset($folders[$idx]);
             }
         }
 
         return $folders;
     }
 
     /**
      * Wrapper for rcube_imap::list_folders() with optional post-filtering
      */
     protected static function _imap_list_folders($root, $mbox)
     {
         $postfilter = null;
 
         // compose a post-filter expression for the excluded namespaces
         if ($root . $mbox == '*' && ($skip_ns = self::$config->get('kolab_skip_namespace'))) {
             $excludes = array();
             foreach ((array)$skip_ns as $ns) {
                 if ($ns_root = self::namespace_root($ns)) {
                     $excludes[] = $ns_root;
                 }
             }
 
             if (count($excludes)) {
                 $postfilter = '!^(' . join(')|(', array_map('preg_quote', $excludes)) . ')!';
             }
         }
 
         // use normal LIST command to return all folders, it's fast enough
         $folders = self::$imap->list_folders($root, $mbox, null, null, !empty($postfilter));
 
         if (!empty($postfilter)) {
             $folders = array_filter($folders, function($folder) use ($postfilter) { return !preg_match($postfilter, $folder); });
             $folders = self::$imap->sort_folder_list($folders);
         }
 
         return $folders;
     }
 
     /**
      * Wrapper for rcube_imap::list_folders_subscribed()
      * with support for temporarily subscribed folders
      */
     protected static function _imap_list_subscribed($root, $mbox, $filter = null)
     {
         $folders = self::$imap->list_folders_subscribed($root, $mbox);
 
         // add temporarily subscribed folders
-        if ($filter != 'mail' && self::$with_tempsubs && is_array($_SESSION['kolab_subscribed_folders'])) {
+        if ($filter != 'mail' && self::$with_tempsubs && is_array($_SESSION['kolab_subscribed_folders'] ?? null)) {
             $folders = array_unique(array_merge($folders, $_SESSION['kolab_subscribed_folders']));
         }
 
         return $folders;
     }
 
     /**
      * Search for shared or otherwise not listed groupware folders the user has access
      *
      * @param string Folder type of folders to search for
      * @param string Search string
      * @param array  Namespace(s) to exclude results from
      *
      * @return array List of matching kolab_storage_folder objects
      */
     public static function search_folders($type, $query, $exclude_ns = array())
     {
         if (!self::setup()) {
             return array();
         }
 
         $folders = array();
         $query = str_replace('*', '', $query);
 
         // find unsubscribed IMAP folders of the given type
         foreach ((array)self::list_folders('', '*', $type, false, $folderdata) as $foldername) {
             // FIXME: only consider the last part of the folder path for searching?
             $realname = strtolower(rcube_charset::convert($foldername, 'UTF7-IMAP'));
             if (($query == '' || strpos($realname, $query) !== false) &&
                 !self::folder_is_subscribed($foldername, true) &&
                 !in_array(self::$imap->folder_namespace($foldername), (array)$exclude_ns)
               ) {
                 $folders[] = new kolab_storage_folder($foldername, $type, $folderdata[$foldername]);
             }
         }
 
         return $folders;
     }
 
     /**
      * Sort the given list of kolab folders by namespace/name
      *
      * @param array List of kolab_storage_folder objects
      * @return array Sorted list of folders
      */
     public static function sort_folders($folders)
     {
         $pad     = '  ';
         $out     = array();
         $nsnames = array('personal' => array(), 'shared' => array(), 'other' => array());
 
         foreach ($folders as $folder) {
             $_folders[$folder->name] = $folder;
             $ns = $folder->get_namespace();
             $nsnames[$ns][$folder->name] = strtolower(html_entity_decode($folder->get_name(), ENT_COMPAT, RCUBE_CHARSET)) . $pad;  // decode &raquo;
         }
 
         // $folders is a result of get_folders() we can assume folders were already sorted
         foreach (array_keys($nsnames) as $ns) {
             asort($nsnames[$ns], SORT_LOCALE_STRING);
             foreach (array_keys($nsnames[$ns]) as $utf7name) {
                 $out[] = $_folders[$utf7name];
             }
         }
 
         return $out;
     }
 
     /**
      * Check the folder tree and add the missing parents as virtual folders
      *
      * @param array $folders Folders list
      * @param object $tree   Reference to the root node of the folder tree
      *
      * @return array Flat folders list
      */
     public static function folder_hierarchy($folders, &$tree = null)
     {
         if (!self::setup()) {
             return array();
         }
 
         $_folders = array();
         $delim    = self::$imap->get_hierarchy_delimiter();
         $other_ns = rtrim(self::namespace_root('other'), $delim);
         $tree     = new kolab_storage_folder_virtual('', '<root>', '');  // create tree root
         $refs     = array('' => $tree);
 
         foreach ($folders as $idx => $folder) {
             $path = explode($delim, $folder->name);
             array_pop($path);
             $folder->parent = join($delim, $path);
             $folder->children = array();  // reset list
 
             // skip top folders or ones with a custom displayname
             if (count($path) < 1 || kolab_storage::custom_displayname($folder->name)) {
                 $tree->children[] = $folder;
             }
             else {
                 $parents = array();
                 $depth = $folder->get_namespace() == 'personal' ? 1 : 2;
 
                 while (count($path) >= $depth && ($parent = join($delim, $path))) {
                     array_pop($path);
                     $parent_parent = join($delim, $path);
 
                     if (!$refs[$parent]) {
                         if ($folder->type && self::folder_type($parent) == $folder->type) {
                             $refs[$parent] = new kolab_storage_folder($parent, $folder->type, $folder->type);
                             $refs[$parent]->parent = $parent_parent;
                         }
                         else if ($parent_parent == $other_ns) {
                             $refs[$parent] = new kolab_storage_folder_user($parent, $parent_parent);
                         }
                         else {
                             $name = kolab_storage::object_name($parent);
                             $refs[$parent] = new kolab_storage_folder_virtual($parent, $name, $folder->get_namespace(), $parent_parent);
                         }
                         $parents[] = $refs[$parent];
                     }
                 }
 
                 if (!empty($parents)) {
                     $parents = array_reverse($parents);
                     foreach ($parents as $parent) {
                         $parent_node = $refs[$parent->parent] ?: $tree;
                         $parent_node->children[] = $parent;
                         $_folders[] = $parent;
                     }
                 }
 
                 $parent_node = $refs[$folder->parent] ?: $tree;
                 $parent_node->children[] = $folder;
             }
 
             $refs[$folder->name] = $folder;
             $_folders[] = $folder;
             unset($folders[$idx]);
         }
 
         return $_folders;
     }
 
     /**
      * Returns folder types indexed by folder name
      *
      * @param string $prefix Folder prefix (Default '*' for all folders)
      *
      * @return array|bool List of folders, False on failure
      */
     public static function folders_typedata($prefix = '*')
     {
         if (!self::setup()) {
             return false;
         }
 
         $type_keys = array(self::CTYPE_KEY, self::CTYPE_KEY_PRIVATE);
 
         // fetch metadata from *some* folders only
         if (($prefix == '*' || $prefix == '') && ($skip_ns = self::$config->get('kolab_skip_namespace'))) {
             $delimiter = self::$imap->get_hierarchy_delimiter();
             $folderdata = $blacklist = array();
             foreach ((array)$skip_ns as $ns) {
                 if ($ns_root = rtrim(self::namespace_root($ns), $delimiter)) {
                     $blacklist[] = $ns_root;
                 }
             }
             foreach (array('personal','other','shared') as $ns) {
                 if (!in_array($ns, (array)$skip_ns)) {
                     $ns_root = rtrim(self::namespace_root($ns), $delimiter);
 
                     // list top-level folders and their childs one by one
                     // GETMETADATA "%" doesn't list shared or other namespace folders but "*" would
                     if ($ns_root == '') {
                         foreach ((array)self::$imap->get_metadata('%', $type_keys) as $folder => $metadata) {
                             if (!in_array($folder, $blacklist)) {
                                 $folderdata[$folder] = $metadata;
                                 $opts = self::$imap->folder_attributes($folder);
                                 if (!in_array('\\HasNoChildren', $opts) && ($data = self::$imap->get_metadata($folder.$delimiter.'*', $type_keys))) {
                                     $folderdata += $data;
                                 }
                             }
                         }
                     }
                     else if ($data = self::$imap->get_metadata($ns_root.$delimiter.'*', $type_keys)) {
                         $folderdata += $data;
                     }
                 }
             }
         }
         else {
             $folderdata = self::$imap->get_metadata($prefix, $type_keys);
         }
 
         if (!is_array($folderdata)) {
             return false;
         }
 
         return array_map(array('kolab_storage', 'folder_select_metadata'), $folderdata);
     }
 
     /**
      * Callback for array_map to select the correct annotation value
      */
     public static function folder_select_metadata($types)
     {
         if (!empty($types[self::CTYPE_KEY_PRIVATE])) {
             return $types[self::CTYPE_KEY_PRIVATE];
         }
         else if (!empty($types[self::CTYPE_KEY])) {
             list($ctype, ) = explode('.', $types[self::CTYPE_KEY]);
             return $ctype;
         }
         return null;
     }
 
     /**
      * Returns type of IMAP folder
      *
      * @param string $folder Folder name (UTF7-IMAP)
      *
      * @return string Folder type
      */
     public static function folder_type($folder)
     {
         self::setup();
 
         $metadata = self::$imap->get_metadata($folder, array(self::CTYPE_KEY, self::CTYPE_KEY_PRIVATE));
 
         if (!is_array($metadata)) {
             return null;
         }
 
         if (!empty($metadata[$folder])) {
             return self::folder_select_metadata($metadata[$folder]);
         }
 
         return 'mail';
     }
 
     /**
      * Sets folder content-type.
      *
      * @param string $folder Folder name
      * @param string $type   Content type
      *
      * @return boolean True on success
      */
     public static function set_folder_type($folder, $type='mail')
     {
         self::setup();
 
         list($ctype, $subtype) = explode('.', $type);
 
         $success = self::$imap->set_metadata($folder, array(self::CTYPE_KEY => $ctype, self::CTYPE_KEY_PRIVATE => $subtype ? $type : null));
 
         if (!$success)  // fallback: only set private annotation
             $success |= self::$imap->set_metadata($folder, array(self::CTYPE_KEY_PRIVATE => $type));
 
         return $success;
     }
 
     /**
      * Check subscription status of this folder
      *
      * @param string $folder Folder name
      * @param boolean $temp  Include temporary/session subscriptions
      *
      * @return boolean True if subscribed, false if not
      */
     public static function folder_is_subscribed($folder, $temp = false)
     {
         if (self::$subscriptions === null) {
             self::setup();
             self::$with_tempsubs = false;
             self::$subscriptions = self::$imap->list_folders_subscribed();
             self::$with_tempsubs = true;
         }
 
         return in_array($folder, self::$subscriptions) ||
             ($temp && in_array($folder, (array)$_SESSION['kolab_subscribed_folders']));
     }
 
     /**
      * Change subscription status of this folder
      *
      * @param string $folder Folder name
      * @param boolean $temp  Only subscribe temporarily for the current session
      *
      * @return True on success, false on error
      */
     public static function folder_subscribe($folder, $temp = false)
     {
         self::setup();
 
         // temporary/session subscription
         if ($temp) {
             if (self::folder_is_subscribed($folder)) {
                 return true;
             }
             else if (!is_array($_SESSION['kolab_subscribed_folders']) || !in_array($folder, $_SESSION['kolab_subscribed_folders'])) {
                 $_SESSION['kolab_subscribed_folders'][] = $folder;
                 return true;
             }
         }
         else if (self::$imap->subscribe($folder)) {
             self::$subscriptions = null;
             return true;
         }
 
         return false;
     }
 
     /**
      * Change subscription status of this folder
      *
      * @param string $folder Folder name
      * @param boolean $temp  Only remove temporary subscription
      *
      * @return True on success, false on error
      */
     public static function folder_unsubscribe($folder, $temp = false)
     {
         self::setup();
 
         // temporary/session subscription
         if ($temp) {
             if (is_array($_SESSION['kolab_subscribed_folders']) && ($i = array_search($folder, $_SESSION['kolab_subscribed_folders'])) !== false) {
                 unset($_SESSION['kolab_subscribed_folders'][$i]);
             }
             return true;
         }
         else if (self::$imap->unsubscribe($folder)) {
             self::$subscriptions = null;
             return true;
         }
 
         return false;
     }
 
     /**
      * Check activation status of this folder
      *
      * @param string $folder Folder name
      *
      * @return boolean True if active, false if not
      */
     public static function folder_is_active($folder)
     {
         $active_folders = self::get_states();
 
         return in_array($folder, $active_folders);
     }
 
     /**
      * Change activation status of this folder
      *
      * @param string $folder Folder name
      *
      * @return True on success, false on error
      */
     public static function folder_activate($folder)
     {
         // activation implies temporary subscription
         self::folder_subscribe($folder, true);
         return self::set_state($folder, true);
     }
 
     /**
      * Change activation status of this folder
      *
      * @param string $folder Folder name
      *
      * @return True on success, false on error
      */
     public static function folder_deactivate($folder)
     {
         // remove from temp subscriptions, really?
         self::folder_unsubscribe($folder, true);
 
         return self::set_state($folder, false);
     }
 
     /**
      * Return list of active folders
      */
     private static function get_states()
     {
         if (self::$states !== null) {
             return self::$states;
         }
 
         $rcube   = rcube::get_instance();
         $folders = $rcube->config->get('kolab_active_folders');
 
         if ($folders !== null) {
             self::$states = !empty($folders) ? explode('**', $folders) : array();
         }
         // for backward-compatibility copy server-side subscriptions to activation states
         else {
             self::setup();
             if (self::$subscriptions === null) {
                 self::$with_tempsubs = false;
                 self::$subscriptions = self::$imap->list_folders_subscribed();
                 self::$with_tempsubs = true;
             }
             self::$states = (array) self::$subscriptions;
             $folders = implode('**', self::$states);
             $rcube->user->save_prefs(array('kolab_active_folders' => $folders));
         }
 
         return self::$states;
     }
 
     /**
      * Update list of active folders
      */
     private static function set_state($folder, $state)
     {
         self::get_states();
 
         // update in-memory list
         $idx = array_search($folder, self::$states);
         if ($state && $idx === false) {
             self::$states[] = $folder;
         }
         else if (!$state && $idx !== false) {
             unset(self::$states[$idx]);
         }
 
         // update user preferences
         $folders = implode('**', self::$states);
 
         return rcube::get_instance()->user->save_prefs(array('kolab_active_folders' => $folders));
     }
 
     /**
      * Creates default folder of specified type
      * To be run when none of subscribed folders (of specified type) is found
      *
      * @param string $type  Folder type
      * @param string $props Folder properties (color, etc)
      *
      * @return string Folder name
      */
     public static function create_default_folder($type, $props = array())
     {
         if (!self::setup()) {
             return;
         }
 
         $folders = self::$imap->get_metadata('*', array(kolab_storage::CTYPE_KEY_PRIVATE));
 
         // from kolab_folders config
         $folder_type  = strpos($type, '.') ? str_replace('.', '_', $type) : $type . '_default';
         $default_name = self::$config->get('kolab_folders_' . $folder_type);
         $folder_type  = str_replace('_', '.', $folder_type);
 
         // check if we have any folder in personal namespace
         // folder(s) may exist but not subscribed
         foreach ((array)$folders as $f => $data) {
             if (strpos($data[self::CTYPE_KEY_PRIVATE], $type) === 0) {
                 $folder = $f;
                 break;
             }
         }
 
         if (!$folder) {
             if (!$default_name) {
                 $default_name = self::$default_folders[$type];
             }
 
             if (!$default_name) {
                 return;
             }
 
             $folder = rcube_charset::convert($default_name, RCUBE_CHARSET, 'UTF7-IMAP');
             $prefix = self::$imap->get_namespace('prefix');
 
             // add personal namespace prefix if needed
             if ($prefix && strpos($folder, $prefix) !== 0 && $folder != 'INBOX') {
                 $folder = $prefix . $folder;
             }
 
             if (!self::$imap->folder_exists($folder)) {
                 if (!self::$imap->create_folder($folder)) {
                     return;
                 }
             }
 
             self::set_folder_type($folder, $folder_type);
         }
 
         self::folder_subscribe($folder);
 
         if ($props['active']) {
             self::set_state($folder, true);
         }
 
         if (!empty($props)) {
             self::set_folder_props($folder, $props);
         }
 
         return $folder;
     }
 
     /**
      * Sets folder metadata properties
      *
      * @param string $folder Folder name
      * @param array  &$prop  Folder properties (color, displayname)
      */
     public static function set_folder_props($folder, &$prop)
     {
         if (!self::setup()) {
             return;
         }
 
         // TODO: also save 'showalarams' and other properties here
         $ns        = self::$imap->folder_namespace($folder);
         $supported = array(
             'color'       => array(self::COLOR_KEY_SHARED, self::COLOR_KEY_PRIVATE),
             'displayname' => array(self::NAME_KEY_SHARED, self::NAME_KEY_PRIVATE),
         );
 
         foreach ($supported as $key => $metakeys) {
             if (array_key_exists($key, $prop)) {
                 $meta_saved = false;
                 if ($ns == 'personal')  // save in shared namespace for personal folders
                     $meta_saved = self::$imap->set_metadata($folder, array($metakeys[0] => $prop[$key]));
                 if (!$meta_saved)    // try in private namespace
                     $meta_saved = self::$imap->set_metadata($folder, array($metakeys[1] => $prop[$key]));
                 if ($meta_saved)
                     unset($prop[$key]);  // unsetting will prevent fallback to local user prefs
             }
         }
     }
 
     /**
      * Search users in Kolab LDAP storage
      *
      * @param mixed   $query    Search value (or array of field => value pairs)
      * @param int     $mode     Matching mode: 0 - partial (*abc*), 1 - strict (=), 2 - prefix (abc*)
      * @param array   $required List of fields that shall ot be empty
      * @param int     $limit    Maximum number of records
      * @param int     $count    Returns the number of records found
      *
      * @return array List of users
      */
     public static function search_users($query, $mode = 1, $required = array(), $limit = 0, &$count = 0)
     {
         $query = str_replace('*', '', $query);
 
         // requires a working LDAP setup
         if (!strlen($query) || !($ldap = self::ldap())) {
             return array();
         }
 
         $root          = self::namespace_root('other');
         $user_attrib   = self::$config->get('kolab_users_id_attrib', self::$config->get('kolab_auth_login', 'mail'));
         $search_attrib = self::$config->get('kolab_users_search_attrib', array('cn','mail','alias'));
 
         // search users using the configured attributes
         $results = $ldap->dosearch($search_attrib, $query, $mode, $required, $limit, $count);
 
         // exclude myself
         if ($_SESSION['kolab_dn']) {
             unset($results[$_SESSION['kolab_dn']]);
         }
 
         // resolve to IMAP folder name
         array_walk($results, function(&$user, $dn) use ($root, $user_attrib) {
             list($localpart, ) = explode('@', $user[$user_attrib]);
             $user['kolabtargetfolder'] = $root . $localpart;
         });
 
         return $results;
     }
 
     /**
      * Returns a list of IMAP folders shared by the given user
      *
      * @param array   User entry from LDAP
      * @param string  Data type to list folders for (contact,event,task,journal,file,note,mail,configuration)
      * @param int     1 - subscribed folders only, 0 - all folders, 2 - all non-active
      * @param array   Will be filled with folder-types data
      *
      * @return array List of folders
      */
     public static function list_user_folders($user, $type, $subscribed = 0, &$folderdata = array())
     {
         self::setup();
 
         $folders = array();
 
         // use localpart of user attribute as root for folder listing
         $user_attrib = self::$config->get('kolab_users_id_attrib', self::$config->get('kolab_auth_login', 'mail'));
         if (!empty($user[$user_attrib])) {
             list($mbox) = explode('@', $user[$user_attrib]);
 
             $delimiter  = self::$imap->get_hierarchy_delimiter();
             $other_ns   = self::namespace_root('other');
             $prefix     = $other_ns . $mbox . $delimiter;
             $subscribed = (int) $subscribed;
             $subs       = $subscribed < 2 ? (bool) $subscribed : false;
             $folders    = self::list_folders($prefix, '*', $type, $subs, $folderdata);
 
             if ($subscribed === 2 && !empty($folders)) {
                 $active = self::get_states();
                 if (!empty($active)) {
                     $folders = array_diff($folders, $active);
                 }
             }
         }
 
         return $folders;
     }
 
     /**
      * Get a list of (virtual) top-level folders from the other users namespace
      *
      * @param string  Data type to list folders for (contact,event,task,journal,file,note,mail,configuration)
      * @param boolean Enable to return subscribed folders only (null to use configured subscription mode)
      *
      * @return array List of kolab_storage_folder_user objects
      */
     public static function get_user_folders($type, $subscribed)
     {
         $folders = $folderdata = array();
 
         if (self::setup()) {
             $delimiter = self::$imap->get_hierarchy_delimiter();
             $other_ns = rtrim(self::namespace_root('other'), $delimiter);
             $path_len = count(explode($delimiter, $other_ns));
 
             foreach ((array)self::list_folders($other_ns . $delimiter, '*', '', $subscribed) as $foldername) {
                 if ($foldername == 'INBOX')  // skip INBOX which is added by default
                     continue;
 
                 $path = explode($delimiter, $foldername);
 
                 // compare folder type if a subfolder is listed
                 if ($type && count($path) > $path_len + 1 && $type != self::folder_type($foldername)) {
                     continue;
                 }
 
                 // truncate folder path to top-level folders of the 'other' namespace
                 $foldername = join($delimiter, array_slice($path, 0, $path_len + 1));
 
                 if (!$folders[$foldername]) {
                     $folders[$foldername] = new kolab_storage_folder_user($foldername, $other_ns);
                 }
             }
 
             // for every (subscribed) user folder, list all (unsubscribed) subfolders
             foreach ($folders as $userfolder) {
                 foreach ((array)self::list_folders($userfolder->name . $delimiter, '*', $type, false, $folderdata) as $foldername) {
                     if (!$folders[$foldername]) {
                         $folders[$foldername] = new kolab_storage_folder($foldername, $type, $folderdata[$foldername]);
                         $userfolder->children[] = $folders[$foldername];
                     }
                 }
             }
         }
 
         return $folders;
     }
 
     /**
      * Handler for user_delete plugin hooks
      *
      * Remove all cache data from the local database related to the given user.
      */
     public static function delete_user_folders($args)
     {
         $db = rcmail::get_instance()->get_dbh();
         $prefix = 'imap://' . urlencode($args['username']) . '@' . $args['host'] . '/%';
         $db->query("DELETE FROM " . $db->table_name('kolab_folders', true) . " WHERE `resource` LIKE ?", $prefix);
 
     }
 
     /**
      * Get folder METADATA for all supported keys
      * Do this in one go for better caching performance
      */
     public static function folder_metadata($folder)
     {
         if (self::setup()) {
             $keys = array(
                 // For better performance we skip displayname here, see (self::custom_displayname())
                 // self::NAME_KEY_PRIVATE,
                 // self::NAME_KEY_SHARED,
                 self::CTYPE_KEY,
                 self::CTYPE_KEY_PRIVATE,
                 self::COLOR_KEY_PRIVATE,
                 self::COLOR_KEY_SHARED,
                 self::UID_KEY_SHARED,
                 self::UID_KEY_CYRUS,
             );
 
             $metadata = self::$imap->get_metadata($folder, $keys);
 
             return $metadata[$folder];
         }
     }
 
     /**
      * Get user attributes for specified other user (imap) folder identifier.
      *
      * @param string $folder_id Folder name w/o path (imap user identifier)
      * @param bool   $as_string Return configured display name attribute value
      *
      * @return array User attributes
      * @see self::ldap()
      */
     public static function folder_id2user($folder_id, $as_string = false)
     {
         static $domain, $cache, $name_attr;
 
         $rcube = rcube::get_instance();
 
         if ($domain === null) {
             list(, $domain) = explode('@', $rcube->get_user_name());
         }
 
         if ($name_attr === null) {
             $name_attr = (array) ($rcube->config->get('kolab_users_name_field', $rcube->config->get('kolab_auth_name')) ?: 'name');
         }
 
         $token = $folder_id;
-        if ($domain && strpos($find, '@') === false) {
+        if ($domain && strpos($token, '@') === false) {
             $token .= '@' . $domain;
         }
 
         if ($cache === null) {
             $cache = $rcube->get_cache_shared('kolab_users') ?: false;
         }
 
         // use value cached in memory for repeated lookups
         if (!$cache && array_key_exists($token, self::$ldapcache)) {
             $user = self::$ldapcache[$token];
         }
 
         if (empty($user) && $cache) {
             $user = $cache->get($token);
         }
 
         if (empty($user) && ($ldap = self::ldap())) {
             $user = $ldap->get_user_record($token, $_SESSION['imap_host']);
 
             if (!empty($user)) {
                 $keys = array('displayname', 'name', 'mail'); // supported keys
                 $user = array_intersect_key($user, array_flip($keys));
 
                 if (!empty($user)) {
                     if ($cache) {
                         $cache->set($token, $user);
                     }
                     else {
                         self::$ldapcache[$token] = $user;
                     }
                 }
             }
         }
 
         if (!empty($user)) {
             if ($as_string) {
                 foreach ($name_attr as $attr) {
                     if ($display = $user[$attr]) {
                         break;
                     }
                 }
 
                 if (!$display) {
                     $display = $user['displayname'] ?: $user['name'];
                 }
 
                 if ($display && $display != $folder_id) {
                     $display = "$display ($folder_id)";
                 }
 
                 return $display;
             }
 
             return $user;
         }
     }
 
     /**
      * Chwala's 'folder_mod' hook handler for mapping other users folder names
      */
     public static function folder_mod($args)
     {
         static $roots;
 
         if ($roots === null) {
             self::setup();
             $roots = self::$imap->get_namespace('other');
         }
 
         // Note: We're working with UTF7-IMAP encoding here
 
         if ($args['dir'] == 'in') {
             foreach ((array) $roots as $root) {
                 if (strpos($args['folder'], $root[0]) === 0) {
                     // remove root and explode folder
                     $delim  = $root[1];
                     $folder = explode($delim, substr($args['folder'], strlen($root[0])));
                     // compare first (user) part with a regexp, it's supposed
                     // to look like this: "Doe, Jane (uid)", so we can extract the uid
                     // and replace the folder with it
                     if (preg_match('~^[^/]+ \(([^)]+)\)$~', $folder[0], $m)) {
                         $folder[0] = $m[1];
                         $args['folder'] = $root[0] . implode($delim, $folder);
                     }
 
                     break;
                 }
             }
         }
         else { // dir == 'out'
             foreach ((array) $roots as $root) {
                 if (strpos($args['folder'], $root[0]) === 0) {
                     // remove root and explode folder
                     $delim  = $root[1];
                     $folder = explode($delim, substr($args['folder'], strlen($root[0])));
 
                     // Replace uid with "Doe, Jane (uid)"
                     if ($user = self::folder_id2user($folder[0], true)) {
                         $user      = str_replace($delim, '', $user);
                         $folder[0] = rcube_charset::convert($user, RCUBE_CHARSET, 'UTF7-IMAP');
 
                         $args['folder'] = $root[0] . implode($delim, $folder);
                     }
 
                     break;
                 }
             }
         }
 
         return $args;
     }
 }
diff --git a/plugins/libkolab/lib/kolab_storage_dav_folder.php b/plugins/libkolab/lib/kolab_storage_dav_folder.php
index 6877bdc5..2a1cda0c 100644
--- a/plugins/libkolab/lib/kolab_storage_dav_folder.php
+++ b/plugins/libkolab/lib/kolab_storage_dav_folder.php
@@ -1,759 +1,759 @@
 <?php
 
 /**
  * A class representing a DAV folder object.
  *
  * @author Aleksander Machniak <machniak@apheleia-it.ch>
  *
  * Copyright (C) 2014-2022, Apheleia IT AG <contact@apheleia-it.ch>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
  * published by the Free Software Foundation, either version 3 of the
  * License, or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU Affero General Public License for more details.
  *
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
 #[AllowDynamicProperties]
 class kolab_storage_dav_folder extends kolab_storage_folder
 {
     public $dav;
     public $href;
     public $attributes;
 
     /**
      * Object constructor
      */
     public function __construct($dav, $attributes, $type = '')
     {
         $this->attributes = $attributes;
 
         $this->href  = $this->attributes['href'];
         $this->id    = kolab_storage_dav::folder_id($dav->url, $this->href);
         $this->dav   = $dav;
         $this->valid = true;
 
         list($this->type, $suffix) = strpos($type, '.') ? explode('.', $type) : [$type, ''];
         $this->default = $suffix == 'default';
         $this->subtype = $this->default ? '' : $suffix;
 
         // Init cache
         $this->cache = kolab_storage_dav_cache::factory($this);
     }
 
     /**
      * Returns the owner of the folder.
      *
      * @param bool Return a fully qualified owner name (i.e. including domain for shared folders)
      *
      * @return string The owner of this folder.
      */
     public function get_owner($fully_qualified = false)
     {
         // return cached value
         if (isset($this->owner)) {
             return $this->owner;
         }
 
         $rcube = rcube::get_instance();
         $this->owner = $rcube->get_user_name();
         $this->valid = true;
 
         // TODO: Support shared folders
 
         return $this->owner;
     }
 
     /**
      * Get a folder Etag identifier
      */
     public function get_ctag()
     {
         return $this->attributes['ctag'];
     }
 
     /**
      * Getter for the name of the namespace to which the folder belongs
      *
      * @return string Name of the namespace (personal, other, shared)
      */
     public function get_namespace()
     {
         // TODO: Support shared folders
         return 'personal';
     }
 
     /**
      * Get the display name value of this folder
      *
      * @return string Folder name
      */
     public function get_name()
     {
         return kolab_storage_dav::object_name($this->attributes['name']);
     }
 
     /**
      * Getter for the top-end folder name (not the entire path)
      *
      * @return string Name of this folder
      */
     public function get_foldername()
     {
         return $this->attributes['name'];
     }
 
     public function get_folder_info()
     {
         return []; // todo ?
     }
 
     /**
      * Getter for parent folder path
      *
      * @return string Full path to parent folder
      */
     public function get_parent()
     {
         // TODO
         return '';
     }
 
     /**
      * Compose a unique resource URI for this folder
      */
     public function get_resource_uri()
     {
         if (!empty($this->resource_uri)) {
             return $this->resource_uri;
         }
 
         // compose fully qualified resource uri for this instance
         $host = preg_replace('|^https?://|', 'dav://' . urlencode($this->get_owner(true)) . '@', $this->dav->url);
         $path = $this->href[0] == '/' ? $this->href : "/{$this->href}";
 
         $host_path = parse_url($host, PHP_URL_PATH);
         if ($host_path && strpos($path, $host_path) === 0) {
             $path = substr($path, strlen($host_path));
         }
 
         $this->resource_uri = unslashify($host) . $path;
 
         return $this->resource_uri;
     }
 
     /**
      * Getter for the Cyrus mailbox identifier corresponding to this folder
      * (e.g. user/john.doe/Calendar/Personal@example.org)
      *
      * @return string Mailbox ID
      */
     public function get_mailbox_id()
     {
         // TODO: This is used with Bonnie related features
         return '';
     }
 
     /**
      * Get the color value stored in metadata
      *
      * @param string Default color value to return if not set
      *
      * @return mixed Color value from the folder metadata or $default if not set
      */
     public function get_color($default = null)
     {
         return !empty($this->attributes['color']) ? $this->attributes['color'] : $default;
     }
 
     /**
      * Get ACL information for this folder
      *
      * @return string Permissions as string
      */
     public function get_myrights()
     {
         // TODO
         return '';
     }
 
     /**
      * Helper method to extract folder UID
      *
      * @return string Folder's UID
      */
     public function get_uid()
     {
         // TODO ???
         return '';
     }
 
     /**
      * Check activation status of this folder
      *
      * @return bool True if enabled, false if not
      */
     public function is_active()
     {
         return true; // Unused
     }
 
     /**
      * Change activation status of this folder
      *
      * @param bool The desired subscription status: true = active, false = not active
      *
      * @return bool True on success, false on error
      */
     public function activate($active)
     {
         return true; // Unused
     }
 
     /**
      * Check subscription status of this folder
      *
      * @return bool True if subscribed, false if not
      */
     public function is_subscribed()
     {
         return true; // TODO
     }
 
     /**
      * Change subscription status of this folder
      *
      * @param bool The desired subscription status: true = subscribed, false = not subscribed
      *
      * @return True on success, false on error
      */
     public function subscribe($subscribed)
     {
         return true; // TODO
     }
 
     /**
      * Delete the specified object from this folder.
      *
      * @param array|string $object  The Kolab object to delete or object UID
      * @param bool         $expunge Should the folder be expunged?
      *
      * @return bool True if successful, false on error
      */
     public function delete($object, $expunge = true)
     {
         if (!$this->valid) {
             return false;
         }
 
         $uid = is_array($object) ? $object['uid'] : $object;
 
         $success = $this->dav->delete($this->object_location($uid));
 
         if ($success) {
             $this->cache->set($uid, false);
         }
 
         return $success;
     }
 
     /**
      * Delete all objects in a folder.
      *
      * Note: This method is used by kolab_addressbook plugin only
      *
      * @return bool True if successful, false on error
      */
     public function delete_all()
     {
         if (!$this->valid) {
             return false;
         }
 
         // TODO: Maybe just deleting and re-creating a folder would be
         //       better, but probably might not always work (ACL)
 
         $this->cache->synchronize();
 
         foreach (array_keys($this->cache->folder_index()) as $uid) {
             $this->dav->delete($this->object_location($uid));
         }
 
         $this->cache->purge();
 
         return true;
     }
 
     /**
      * Restore a previously deleted object
      *
      * @param string $uid Object UID
      *
      * @return mixed Message UID on success, false on error
      */
     public function undelete($uid)
     {
         if (!$this->valid) {
             return false;
         }
 
         // TODO
 
         return false;
     }
 
     /**
      * Move a Kolab object message to another IMAP folder
      *
      * @param string                   Object UID
      * @param kolab_storage_dav_folder Target folder to move object into
      *
      * @return bool True on success, false on failure
      */
     public function move($uid, $target_folder)
     {
         if (!$this->valid) {
             return false;
         }
 
         $source = $this->object_location($uid);
         $target = $target_folder->object_location($uid);
 
         $success = $this->dav->move($source, $target) !== false;
 
         if ($success) {
             $this->cache->set($uid, false);
         }
 
         return $success;
     }
 
     /**
      * Save an object in this folder.
      *
      * @param array  $object The array that holds the data of the object.
      * @param string $type   The type of the kolab object.
      * @param string $uid    The UID of the old object if it existed before
      *
      * @return mixed False on error or object UID on success
      */
     public function save(&$object, $type = null, $uid = null)
     {
         if (!$this->valid || empty($object)) {
             return false;
         }
 
         if (!$type) {
             $type = $this->type;
         }
 
         $result = false;
 
         if (empty($uid)) {
             if (empty($object['created'])) {
                 $object['created'] = new DateTime('now');
             }
         }
         else {
             $object['changed'] = new DateTime('now');
         }
 
         // generate and save object message
         if ($content = $this->to_dav($object)) {
             $method   = $uid ? 'update' : 'create';
             $dav_type = $this->get_dav_type();
             $result   = $this->dav->{$method}($this->object_location($object['uid']), $content, $dav_type);
 
             // Note: $result can be NULL if the request was successful, but ETag wasn't returned
             if ($result !== false) {
                 // insert/update object in the cache
                 $object['etag'] = $result;
                 $object['_raw'] = $content;
                 $this->cache->save($object, $uid);
                 $result = true;
                 unset($object['_raw']);
             }
         }
 
         return $result;
     }
 
     /**
      * Fetch the object the DAV server and convert to internal format
      *
      * @param string The object UID to fetch
      * @param string The object type expected (use wildcard '*' to accept all types)
      * @param string Unused (kept for compat. with the parent class)
      *
      * @return mixed Hash array representing the Kolab object, a kolab_format instance or false if not found
      */
     public function read_object($uid, $type = null, $folder = null)
     {
         if (!$this->valid) {
             return false;
         }
 
         $href    = $this->object_location($uid);
         $objects = $this->dav->getData($this->href, $this->get_dav_type(), [$href]);
 
         if (!is_array($objects) || count($objects) != 1) {
             rcube::raise_error([
                     'code' => 900,
                     'message' => "Failed to fetch {$href}"
                 ], true);
             return false;
         }
 
         return $this->from_dav($objects[0]);
     }
 
     /**
      * Fetch multiple objects from the DAV server and convert to internal format
      *
      * @param array The object UIDs to fetch
      *
      * @return mixed Hash array representing the Kolab objects
      */
     public function read_objects($uids)
     {
         if (!$this->valid) {
             return false;
         }
 
         if (empty($uids)) {
             return [];
         }
 
         foreach ($uids as $uid) {
             $hrefs[] = $this->object_location($uid);
         }
 
         $objects = $this->dav->getData($this->href, $this->get_dav_type(), $hrefs);
 
         if (!is_array($objects)) {
             rcube::raise_error([
                     'code' => 900,
-                    'message' => "Failed to fetch {$href}"
+                    'message' => "Failed to fetch {$this->href}"
                 ], true);
             return false;
         }
 
         $objects = array_map([$this, 'from_dav'], $objects);
 
         foreach ($uids as $idx => $uid) {
             foreach ($objects as $oidx => $object) {
                 if ($object && $object['uid'] == $uid) {
                     $uids[$idx] = $object;
                     unset($objects[$oidx]);
                     continue 2;
                 }
             }
 
             $uids[$idx] = false;
         }
 
         return $uids;
     }
 
     /**
      * Convert DAV object into PHP array
      *
      * @param array Object data in kolab_dav_client::fetchData() format
      *
      * @return array|false Object properties, False on error
      */
     public function from_dav($object)
     {
         if (empty($object ) || empty($object['data'])) {
             return false;
         }
 
         if ($this->type == 'event' || $this->type == 'task') {
             $ical = libcalendaring::get_ical();
             $objects = $ical->import($object['data']);
 
             if (!count($objects) || empty($objects[0]['uid'])) {
                 return false;
             }
 
             $result = $objects[0];
 
             $result['_attachments'] = $result['attachments'] ?? [];
             unset($result['attachments']);
         }
         else if ($this->type == 'contact') {
             if (stripos($object['data'], 'BEGIN:VCARD') !== 0) {
                 return false;
             }
 
             // vCard properties not supported by rcube_vcard
             $map = [
                 'uid'      => 'UID',
                 'kind'     => 'KIND',
                 'member'   => 'MEMBER',
                 'x-kind'   => 'X-ADDRESSBOOKSERVER-KIND',
                 'x-member' => 'X-ADDRESSBOOKSERVER-MEMBER',
             ];
 
             // TODO: We should probably use Sabre/Vobject to parse the vCard
 
             $vcard = new rcube_vcard($object['data'], RCUBE_CHARSET, false, $map);
 
             if (!empty($vcard->displayname) || !empty($vcard->surname) || !empty($vcard->firstname) || !empty($vcard->email)) {
                 $result = $vcard->get_assoc();
 
                 // Contact groups
                 if (!empty($result['x-kind']) && implode($result['x-kind']) == 'group') {
                     $result['_type'] = 'group';
                     $members = isset($result['x-member']) ? $result['x-member'] : [];
                     unset($result['x-kind'], $result['x-member']);
                 }
                 else if (!empty($result['kind']) && implode($result['kind']) == 'group') {
                     $result['_type'] = 'group';
                     $members = isset($result['member']) ? $result['member'] : [];
                     unset($result['kind'], $result['member']);
                 }
 
                 if (isset($members)) {
                     $result['member'] = [];
                     foreach ($members as $member) {
                         if (strpos($member, 'urn:uuid:') === 0) {
                             $result['member'][] = ['uid' => substr($member, 9)];
                         }
                         else if (strpos($member, 'mailto:') === 0) {
                             $member = reset(rcube_mime::decode_address_list(urldecode(substr($member, 7))));
                             if (!empty($member['mailto'])) {
                                 $result['member'][] = ['email' => $member['mailto'], 'name' => $member['name']];
                             }
                         }
                     }
                 }
 
                 if (!empty($result['uid'])) {
                     $result['uid'] = preg_replace('/^urn:uuid:/', '', implode($result['uid']));
                 }
             }
             else {
                 return false;
             }
         }
 
         $result['etag'] = $object['etag'];
         $result['href'] = !empty($object['href']) ? $object['href'] : null;
         $result['uid']  = !empty($object['uid']) ? $object['uid'] : $result['uid'];
 
         return $result;
     }
 
     /**
      * Convert Kolab object into DAV format (iCalendar)
      */
     public function to_dav($object)
     {
         $result = '';
 
         if ($this->type == 'event' || $this->type == 'task') {
             $ical = libcalendaring::get_ical();
 
             if (!empty($object['exceptions'])) {
                 $object['recurrence']['EXCEPTIONS'] = $object['exceptions'];
             }
 
             $object['_type'] = $this->type;
 
             // pre-process attachments
             if (isset($object['_attachments']) && is_array($object['_attachments'])) {
                 foreach ($object['_attachments'] as $key => $attachment) {
                     if ($attachment === false) {
                         // Deleted attachment
                         unset($object['_attachments'][$key]);
                         continue;
                     }
 
                     // make sure size is set
                     if (!isset($attachment['size'])) {
                         if (!empty($attachment['data'])) {
                             if (is_resource($attachment['data'])) {
                                 // this need to be a seekable resource, otherwise
                                 // fstat() fails and we're unable to determine size
                                 // here nor in rcube_imap_generic before IMAP APPEND
                                 $stat = fstat($attachment['data']);
                                 $attachment['size'] = $stat ? $stat['size'] : 0;
                             }
                             else {
                                 $attachment['size'] = strlen($attachment['data']);
                             }
                         }
                         else if (!empty($attachment['path'])) {
                             $attachment['size'] = filesize($attachment['path']);
                         }
 
                         $object['_attachments'][$key] = $attachment;
                     }
                 }
             }
 
             $object['attachments'] = $object['_attachments'] ?? [];
             unset($object['_attachments']);
 
             $result = $ical->export([$object], null, false, [$this, 'get_attachment']);
         }
         else if ($this->type == 'contact') {
             // copy values into vcard object
             // TODO: We should probably use Sabre/Vobject to create the vCard
 
             // vCard properties not supported by rcube_vcard
             $map   = ['uid' => 'UID', 'kind' => 'KIND'];
             $vcard = new rcube_vcard('', RCUBE_CHARSET, false, $map);
 
             if ((!empty($object['_type']) && $object['_type'] == 'group')
                 || (!empty($object['type']) && $object['type'] == 'group')
             ) {
                 $object['kind'] = 'group';
             }
 
             foreach ($object as $key => $values) {
                 list($field, $section) = rcube_utils::explode(':', $key);
 
                 // avoid casting DateTime objects to array
                 if (is_object($values) && $values instanceof DateTimeInterface) {
                     $values = [$values];
                 }
 
                 foreach ((array) $values as $value) {
                     if (isset($value)) {
                         $vcard->set($field, $value, $section);
                     }
                 }
             }
 
             $result = $vcard->export(false);
 
             if (!empty($object['kind']) && $object['kind'] == 'group') {
                 $members = '';
                 foreach ((array) $object['member'] as $member) {
                     $value = null;
                     if (!empty($member['uid'])) {
                         $value = 'urn:uuid:' . $member['uid'];
                     }
                     else if (!empty($member['email']) && !empty($member['name'])) {
                         $value = 'mailto:' . urlencode(sprintf('"%s" <%s>', addcslashes($member['name'], '"'), $member['email']));
                     }
                     else if (!empty($member['email'])) {
                         $value = 'mailto:' . $member['email'];
                     }
 
                     if ($value) {
                         $members .= "MEMBER:{$value}\r\n";
                     }
                 }
 
                 if ($members) {
                     $result = preg_replace('/\r\nEND:VCARD/', "\r\n{$members}END:VCARD", $result);
                 }
 
                 /**
                     Version 4.0 of the vCard format requires Cyrus >= 3.6.0, we'll use Version 3.0 for now
 
                 $result = preg_replace('/\r\nVERSION:3\.0\r\n/', "\r\nVERSION:4.0\r\n", $result);
                 $result = preg_replace('/\r\nN:[^\r]+/', '', $result);
                 $result = preg_replace('/\r\nUID:([^\r]+)/', "\r\nUID:urn:uuid:\\1", $result);
                 */
 
                 $result = preg_replace('/\r\nMEMBER:([^\r]+)/', "\r\nX-ADDRESSBOOKSERVER-MEMBER:\\1", $result);
                 $result = preg_replace('/\r\nKIND:([^\r]+)/', "\r\nX-ADDRESSBOOKSERVER-KIND:\\1", $result);
             }
         }
 
         if ($result) {
             // The content must be UTF-8, otherwise if we try to fetch the object
             // from server XML parsing would fail.
             $result = rcube_charset::clean($result);
         }
 
         return $result;
     }
 
     public function object_location($uid)
     {
         return unslashify($this->href) . '/' . urlencode($uid) . '.' . $this->get_dav_ext();
     }
 
     /**
      * Get a folder DAV content type
      */
     public function get_dav_type()
     {
         return kolab_storage_dav::get_dav_type($this->type);
     }
 
     /**
      * Get body of an attachment
      */
     public function get_attachment($id, $event, $unused1 = null, $unused2 = false, $unused3 = null, $unused4 = false)
     {
         // Note: 'attachments' is defined when saving the data into the DAV server
         //       '_attachments' is defined after fetching the object from the DAV server
         if (is_int($id) && isset($event['attachments'][$id])) {
             $attachment = $event['attachments'][$id];
         }
         else if (is_int($id) && isset($event['_attachments'][$id])) {
             $attachment = $event['_attachments'][$id];
         }
         else if (is_string($id) && !empty($event['attachments'])) {
             foreach ($event['attachments'] as $att) {
                 if (!empty($att['id']) && $att['id'] === $id) {
                     $attachment = $att;
                 }
             }
         }
         else if (is_string($id) && !empty($event['_attachments'])) {
             foreach ($event['_attachments'] as $att) {
                 if (!empty($att['id']) && $att['id'] === $id) {
                     $attachment = $att;
                 }
             }
         }
 
         if (empty($attachment)) {
             return false;
         }
 
         if (!empty($attachment['path'])) {
             return file_get_contents($attachment['path']);
         }
 
         return $attachment['data'] ?? null;
     }
 
     /**
      * Get a DAV file extension for specified Kolab type
      */
     public function get_dav_ext()
     {
         $types = [
             'event' => 'ics',
             'task'  => 'ics',
             'contact' => 'vcf',
         ];
 
         return $types[$this->type];
     }
 
     /**
      * Return folder name as string representation of this object
      *
      * @return string Folder display name
      */
     public function __toString()
     {
         return $this->attributes['name'];
     }
 }
diff --git a/plugins/libkolab/lib/kolab_storage_folder.php b/plugins/libkolab/lib/kolab_storage_folder.php
index 4ef538b8..4d1132f6 100644
--- a/plugins/libkolab/lib/kolab_storage_folder.php
+++ b/plugins/libkolab/lib/kolab_storage_folder.php
@@ -1,1171 +1,1177 @@
 <?php
 
 /**
  * The kolab_storage_folder class represents an IMAP folder on the Kolab server.
  *
  * @version @package_version@
  * @author Thomas Bruederli <bruederli@kolabsys.com>
  * @author Aleksander Machniak <machniak@kolabsys.com>
  *
  * Copyright (C) 2012-2013, Kolab Systems AG <contact@kolabsys.com>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
  * published by the Free Software Foundation, either version 3 of the
  * License, or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU Affero General Public License for more details.
  *
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 class kolab_storage_folder extends kolab_storage_folder_api
 {
     /**
      * The kolab_storage_cache instance for caching operations
      * @var object
      */
     public $cache;
 
     /**
      * Indicate validity status
      * @var boolean
      */
     public $valid = false;
 
+    /**
+     * Indicate virtual status
+     * @var boolean
+     */
+    public $virtual = false;
+
     protected $error = 0;
     protected $resource_uri;
 
 
     /**
      * Default constructor
      *
      * @param string The folder name/path
      * @param string Expected folder type
      * @param string Optional folder type if known
      */
     function __construct($name, $type = null, $type_annotation = null)
     {
         parent::__construct($name);
         $this->set_folder($name, $type, $type_annotation);
     }
 
     /**
      * Set the IMAP folder this instance connects to
      *
      * @param string The folder name/path
      * @param string Expected folder type
      * @param string Optional folder type if known
      */
     public function set_folder($name, $type = null, $type_annotation = null)
     {
         $this->name = $name;
 
         if (empty($type_annotation)) {
             $type_annotation = $this->get_type();
         }
 
         $oldtype = $this->type;
         list($this->type, $suffix) = explode('.', $type_annotation);
         $this->default      = $suffix == 'default';
         $this->subtype      = $this->default ? '' : $suffix;
         $this->id           = kolab_storage::folder_id($name);
         $this->valid        = !empty($this->type) && $this->type != 'mail' && (!$type || $this->type == $type);
 
         if (!$this->valid) {
             $this->error = $this->imap->get_error_code() < 0 ? kolab_storage::ERROR_IMAP_CONN : kolab_storage::ERROR_INVALID_FOLDER;
         }
 
         // reset cached object properties
         $this->owner = $this->namespace = $this->resource_uri = $this->info = $this->idata = null;
 
         // get a new cache instance if folder type changed
         if (!$this->cache || $this->type != $oldtype)
             $this->cache = kolab_storage_cache::factory($this);
         else
             $this->cache->set_folder($this);
 
         $this->imap->set_folder($this->name);
     }
 
     /**
      * Returns code of last error
      *
      * @return int Error code
      */
     public function get_error()
     {
         return $this->error ?: $this->cache->get_error();
     }
 
     /**
      * Check IMAP connection error state
      */
     public function check_error()
     {
         if (($err_code = $this->imap->get_error_code()) < 0) {
             $this->error = kolab_storage::ERROR_IMAP_CONN;
             if (($res_code = $this->imap->get_response_code()) !== 0 && in_array($res_code, array(rcube_storage::NOPERM, rcube_storage::READONLY))) {
                 $this->error = kolab_storage::ERROR_NO_PERMISSION;
             }
         }
 
         return $this->error;
     }
 
     /**
      * Compose a unique resource URI for this IMAP folder
      */
     public function get_resource_uri()
     {
         if (!empty($this->resource_uri)) {
             return $this->resource_uri;
         }
 
         // strip namespace prefix from folder name
         $ns     = $this->get_namespace();
         $nsdata = $this->imap->get_namespace($ns);
 
         if (is_array($nsdata[0]) && strlen($nsdata[0][0]) && strpos($this->name, $nsdata[0][0]) === 0) {
             $subpath = substr($this->name, strlen($nsdata[0][0]));
             if ($ns == 'other') {
                 list($user, $suffix) = explode($nsdata[0][1], $subpath, 2);
                 $subpath = $suffix;
             }
         }
         else {
             $subpath = $this->name;
         }
 
         // compose fully qualified ressource uri for this instance
         $this->resource_uri = 'imap://' . urlencode($this->get_owner(true)) . '@' . $this->imap->options['host'] . '/' . $subpath;
         return $this->resource_uri;
     }
 
     /**
      * Helper method to extract folder UID metadata
      *
      * @return string Folder's UID
      */
     public function get_uid()
     {
         // UID is defined in folder METADATA
         $metakeys = array(kolab_storage::UID_KEY_SHARED, kolab_storage::UID_KEY_CYRUS);
         $metadata = $this->get_metadata();
 
         if ($metadata !== null) {
             foreach ($metakeys as $key) {
                 if ($uid = $metadata[$key]) {
                     return $uid;
                 }
             }
 
             // generate a folder UID and set it to IMAP
             $uid = rtrim(chunk_split(md5($this->name . $this->get_owner() . uniqid('-', true)), 12, '-'), '-');
             if ($this->set_uid($uid)) {
                 return $uid;
             }
         }
 
         $this->check_error();
 
         // create hash from folder name if we can't write the UID metadata
         return md5($this->name . $this->get_owner());
     }
 
     /**
      * Helper method to set an UID value to the given IMAP folder instance
      *
      * @param string Folder's UID
      * @return boolean True on succes, False on failure
      */
     public function set_uid($uid)
     {
         $success = $this->set_metadata(array(kolab_storage::UID_KEY_SHARED => $uid));
 
         $this->check_error();
         return $success;
     }
 
     /**
      * Compose a folder Etag identifier
      */
     public function get_ctag()
     {
         $fdata = $this->get_imap_data();
         $this->check_error();
         return sprintf('%d-%d-%d', $fdata['UIDVALIDITY'], $fdata['HIGHESTMODSEQ'], $fdata['UIDNEXT']);
     }
 
     /**
      * Check activation status of this folder
      *
      * @return boolean True if enabled, false if not
      */
     public function is_active()
     {
         return kolab_storage::folder_is_active($this->name);
     }
 
     /**
      * Change activation status of this folder
      *
      * @param boolean The desired subscription status: true = active, false = not active
      *
      * @return True on success, false on error
      */
     public function activate($active)
     {
         return $active ? kolab_storage::folder_activate($this->name) : kolab_storage::folder_deactivate($this->name);
     }
 
     /**
      * Check subscription status of this folder
      *
      * @return boolean True if subscribed, false if not
      */
     public function is_subscribed()
     {
         return kolab_storage::folder_is_subscribed($this->name);
     }
 
     /**
      * Change subscription status of this folder
      *
      * @param boolean The desired subscription status: true = subscribed, false = not subscribed
      *
      * @return True on success, false on error
      */
     public function subscribe($subscribed)
     {
         return $subscribed ? kolab_storage::folder_subscribe($this->name) : kolab_storage::folder_unsubscribe($this->name);
     }
 
     /**
      * Get number of objects stored in this folder
      *
      * @param mixed Pseudo-SQL query as list of filter parameter triplets
      *    or string with object type (e.g. contact, event, todo, journal, note, configuration)
      *
      * @return integer The number of objects of the given type
      * @see self::select()
      */
     public function count($query = null)
     {
         if (!$this->valid) {
             return 0;
         }
 
         // synchronize cache first
         $this->cache->synchronize();
 
         return $this->cache->count($this->_prepare_query($query));
     }
 
     /**
      * List Kolab objects matching the given query
      *
      * @param mixed Pseudo-SQL query as list of filter parameter triplets
      *    or string with object type (e.g. contact, event, todo, journal, note, configuration)
      *
      * @return array List of Kolab data objects (each represented as hash array)
      * @deprecated Use select()
      */
     public function get_objects($query = array())
     {
         return $this->select($query);
     }
 
     /**
      * Select Kolab objects matching the given query
      *
      * @param mixed   Pseudo-SQL query as list of filter parameter triplets
      *                or string with object type (e.g. contact, event, todo, journal, note, configuration)
      * @param boolean Use fast mode to fetch only minimal set of information
      *                (no xml fetching and parsing, etc.)
      *
      * @return array List of Kolab data objects (each represented as hash array)
      */
     public function select($query = array(), $fast = false)
     {
         if (!$this->valid) {
             return array();
         }
 
         // synchronize caches
         $this->cache->synchronize();
 
         // fetch objects from cache
         return $this->cache->select($this->_prepare_query($query), false, $fast);
     }
 
     /**
      * Getter for object UIDs only
      *
      * @param array Pseudo-SQL query as list of filter parameter triplets
      * @return array List of Kolab object UIDs
      */
     public function get_uids($query = array())
     {
         if (!$this->valid) {
             return array();
         }
 
         // synchronize caches
         $this->cache->synchronize();
 
         // fetch UIDs from cache
         return $this->cache->select($this->_prepare_query($query), true);
     }
 
     /**
      * Setter for ORDER BY and LIMIT parameters for cache queries
      *
      * @param array   List of columns to order by
      * @param integer Limit result set to this length
      * @param integer Offset row
      */
     public function set_order_and_limit($sortcols, $length = null, $offset = 0)
     {
         $this->cache->set_order_by($sortcols);
 
         if ($length !== null) {
             $this->cache->set_limit($length, $offset);
         }
     }
 
     /**
      * Helper method to sanitize query arguments
      */
     private function _prepare_query($query)
     {
         // string equals type query
         // FIXME: should not be called this way!
         if (is_string($query)) {
             return $this->cache->has_type_col() && !empty($query) ? array(array('type','=',$query)) : array();
         }
 
         foreach ((array)$query as $i => $param) {
             if ($param[0] == 'type' && !$this->cache->has_type_col()) {
                 unset($query[$i]);
             }
             else if (($param[0] == 'dtstart' || $param[0] == 'dtend' || $param[0] == 'changed')) {
                 if (is_object($param[2]) && $param[2] instanceof DateTimeInterface) {
                     $param[2] = $param[2]->format('U');
                 }
                 if (is_numeric($param[2])) {
                     $query[$i][2] = date('Y-m-d H:i:s', $param[2]);
                 }
             }
         }
 
         return $query;
     }
 
     /**
      * Getter for a single Kolab object identified by its UID
      *
      * @param string $uid Object UID
      *
      * @return array The Kolab object represented as hash array
      */
     public function get_object($uid)
     {
         if (!$this->valid || !$uid) {
             return false;
         }
 
         // synchronize caches
         $this->cache->synchronize();
 
         return $this->cache->get_by_uid($uid);
     }
 
     /**
      * Fetch a Kolab object attachment which is stored in a separate part
      * of the mail MIME message that represents the Kolab record.
      *
      * @param string   Object's UID
      * @param string   The attachment's mime number
      * @param string   IMAP folder where message is stored;
      *                 If set, that also implies that the given UID is an IMAP UID
      * @param bool     True to print the part content
      * @param resource File pointer to save the message part
      * @param boolean  Disables charset conversion
      *
      * @return mixed  The attachment content as binary string
      */
     public function get_attachment($uid, $part, $mailbox = null, $print = false, $fp = null, $skip_charset_conv = false)
     {
         if ($this->valid && ($msguid = ($mailbox ? $uid : $this->cache->uid2msguid($uid)))) {
             $this->imap->set_folder($mailbox ? $mailbox : $this->name);
 
             if (substr($part, 0, 2) == 'i:') {
                 // attachment data is stored in XML
                 if ($object = $this->cache->get($msguid)) {
                     // load data from XML (attachment content is not stored in cache)
                     if ($object['_formatobj'] && isset($object['_size'])) {
                         $object['_attachments'] = array();
                         $object['_formatobj']->get_attachments($object);
                     }
 
                     foreach ($object['_attachments'] as $attach) {
                         if ($attach['id'] == $part) {
                             if ($print)   echo $attach['content'];
                             else if ($fp) fwrite($fp, $attach['content']);
                             else          return $attach['content'];
                             return true;
                         }
                     }
                 }
             }
             else {
                 // return message part from IMAP directly
                 // TODO: We could improve performance if we cache part's encoding
                 //       without 3rd argument get_message_part() will request BODYSTRUCTURE from IMAP
                 return $this->imap->get_message_part($msguid, $part, null, $print, $fp, $skip_charset_conv);
             }
         }
 
         return null;
     }
 
     /**
      * Fetch the mime message from the storage server and extract
      * the Kolab groupware object from it
      *
      * @param string The IMAP message UID to fetch
      * @param string The object type expected (use wildcard '*' to accept all types)
      * @param string The folder name where the message is stored
      *
      * @return mixed Hash array representing the Kolab object, a kolab_format instance or false if not found
      */
     public function read_object($msguid, $type = null, $folder = null)
     {
         if (!$this->valid) {
             return false;
         }
 
         if (!$type) $type = $this->type;
         if (!$folder) $folder = $this->name;
 
         $this->imap->set_folder($folder);
 
         $this->cache->imap_mode(true);
         $message = new rcube_message($msguid);
         $this->cache->imap_mode(false);
 
         // Message doesn't exist?
         if (empty($message->headers)) {
             return false;
         }
 
         // extract the X-Kolab-Type header from the XML attachment part if missing
         if (empty($message->headers->others['x-kolab-type'])) {
             foreach ((array)$message->attachments as $part) {
                 if (strpos($part->mimetype, kolab_format::KTYPE_PREFIX) === 0) {
                     $message->headers->others['x-kolab-type'] = $part->mimetype;
                     break;
                 }
             }
         }
         // fix buggy messages stating the X-Kolab-Type header twice
         else if (is_array($message->headers->others['x-kolab-type'])) {
             $message->headers->others['x-kolab-type'] = reset($message->headers->others['x-kolab-type']);
         }
 
         // no object type header found: abort
         if (empty($message->headers->others['x-kolab-type'])) {
             rcube::raise_error(array(
                 'code' => 600,
                 'type' => 'php',
                 'file' => __FILE__,
                 'line' => __LINE__,
                 'message' => "No X-Kolab-Type information found in message $msguid ($this->name).",
             ), true);
             return false;
         }
 
         $object_type  = kolab_format::mime2object_type($message->headers->others['x-kolab-type']);
         $content_type = kolab_format::KTYPE_PREFIX . $object_type;
 
         // check object type header and abort on mismatch
         if ($type != '*' && strpos($object_type, $type) !== 0 && !($object_type == 'distribution-list' && $type == 'contact')) {
             return false;
         }
 
         $attachments = array();
 
         // get XML part
         foreach ((array)$message->attachments as $part) {
             if (!$xml && ($part->mimetype == $content_type || preg_match('!application/([a-z.]+\+)?xml!i', $part->mimetype))) {
                 $xml = $message->get_part_body($part->mime_id, true);
             }
             else if ($part->filename || $part->content_id) {
                 $key  = $part->content_id ? trim($part->content_id, '<>') : $part->filename;
                 $size = null;
 
                 // Use Content-Disposition 'size' as for the Kolab Format spec.
                 if (isset($part->d_parameters['size'])) {
                     $size = $part->d_parameters['size'];
                 }
                 // we can trust part size only if it's not encoded
                 else if ($part->encoding == 'binary' || $part->encoding == '7bit' || $part->encoding == '8bit') {
                     $size = $part->size;
                 }
 
                 $attachments[$key] = array(
                     'id'       => $part->mime_id,
                     'name'     => $part->filename,
                     'mimetype' => $part->mimetype,
                     'size'     => $size,
                 );
             }
         }
 
         if (!$xml) {
             rcube::raise_error(array(
                 'code' => 600,
                 'type' => 'php',
                 'file' => __FILE__,
                 'line' => __LINE__,
                 'message' => "Could not find Kolab data part in message $msguid ($this->name).",
             ), true);
             return false;
         }
 
         // check kolab format version
         $format_version = $message->headers->others['x-kolab-mime-version'];
         if (empty($format_version)) {
             list($xmltype, $subtype) = explode('.', $object_type);
             $xmlhead = substr($xml, 0, 512);
 
             // detect old Kolab 2.0 format
             if (strpos($xmlhead, '<' . $xmltype) !== false && strpos($xmlhead, 'xmlns=') === false)
                 $format_version = '2.0';
             else
                 $format_version = '3.0'; // assume 3.0
         }
 
         // get Kolab format handler for the given type
         $format = kolab_format::factory($object_type, $format_version);
 
         if (is_a($format, 'PEAR_Error'))
             return false;
 
         // load Kolab object from XML part
         $format->load($xml);
 
         if ($format->is_valid()) {
             $object = $format->to_array(array('_attachments' => $attachments));
             $object['_type']      = $object_type;
             $object['_msguid']    = $msguid;
             $object['_mailbox']   = $this->name;
             $object['_formatobj'] = $format;
             $object['_size']      = strlen($xml);
 
             return $object;
         }
         else {
             // try to extract object UID from XML block
             if (preg_match('!<uid>(.+)</uid>!Uims', $xml, $m))
                 $msgadd = " UID = " . trim(strip_tags($m[1]));
 
             rcube::raise_error(array(
                 'code' => 600,
                 'type' => 'php',
                 'file' => __FILE__,
                 'line' => __LINE__,
                 'message' => "Could not parse Kolab object data in message $msguid ($this->name)." . $msgadd,
             ), true);
 
             self::save_user_xml("$msguid.xml", $xml);
         }
 
         return false;
     }
 
     /**
      * Save an object in this folder.
      *
      * @param array  $object The array that holds the data of the object.
      * @param string $type   The type of the kolab object.
      * @param string $uid    The UID of the old object if it existed before
      *
      * @return mixed False on error or IMAP message UID on success
      */
     public function save(&$object, $type = null, $uid = null)
     {
         if (!$this->valid || empty($object)) {
             return false;
         }
 
         if (!$type)
             $type = $this->type;
 
         // copy attachments from old message
         $copyfrom = $object['_copyfrom'] ?: $object['_msguid'];
         if (!empty($copyfrom) && ($old = $this->cache->get($copyfrom, $type, $object['_mailbox']))) {
             foreach ((array)$old['_attachments'] as $key => $att) {
                 if (!isset($object['_attachments'][$key])) {
                     $object['_attachments'][$key] = $old['_attachments'][$key];
                 }
                 // unset deleted attachment entries
                 if ($object['_attachments'][$key] == false) {
                     unset($object['_attachments'][$key]);
                 }
                 // load photo.attachment from old Kolab2 format to be directly embedded in xcard block
                 else if ($type == 'contact' && ($key == 'photo.attachment' || $key == 'kolab-picture.png') && $att['id']) {
                     if (!isset($object['photo']))
                         $object['photo'] = $this->get_attachment($copyfrom, $att['id'], $object['_mailbox']);
                     unset($object['_attachments'][$key]);
                 }
             }
         }
 
         // save contact photo to attachment for Kolab2 format
         if (kolab_storage::$version == '2.0' && $object['photo']) {
             $attkey = 'kolab-picture.png';  // this file name is hard-coded in libkolab/kolabformatV2/contact.cpp
             $object['_attachments'][$attkey] = array(
                 'mimetype'=> rcube_mime::image_content_type($object['photo']),
                 'content' => preg_match('![^a-z0-9/=+-]!i', $object['photo']) ? $object['photo'] : base64_decode($object['photo']),
             );
         }
 
         // process attachments
         if (is_array($object['_attachments'])) {
             $numatt = count($object['_attachments']);
             foreach ($object['_attachments'] as $key => $attachment) {
                 // FIXME: kolab_storage and Roundcube attachment hooks use different fields!
                 if (empty($attachment['content']) && !empty($attachment['data'])) {
                     $attachment['content'] = $attachment['data'];
                     unset($attachment['data'], $object['_attachments'][$key]['data']);
                 }
 
                 // make sure size is set, so object saved in cache contains this info
                 if (!isset($attachment['size'])) {
                     if (!empty($attachment['content'])) {
                         if (is_resource($attachment['content'])) {
                             // this need to be a seekable resource, otherwise
                             // fstat() failes and we're unable to determine size
                             // here nor in rcube_imap_generic before IMAP APPEND
                             $stat = fstat($attachment['content']);
                             $attachment['size'] = $stat ? $stat['size'] : 0;
                         }
                         else {
                             $attachment['size'] = strlen($attachment['content']);
                         }
                     }
                     else if (!empty($attachment['path'])) {
                         $attachment['size'] = filesize($attachment['path']);
                     }
                     $object['_attachments'][$key] = $attachment;
                 }
 
                 // generate unique keys (used as content-id) for attachments
                 if (is_numeric($key) && $key < $numatt) {
                     // derrive content-id from attachment file name
                     $ext = preg_match('/(\.[a-z0-9]{1,6})$/i', $attachment['name'], $m) ? $m[1] : null;
                     $basename = preg_replace('/[^a-z0-9_.-]/i', '', basename($attachment['name'], $ext));  // to 7bit ascii
                     if (!$basename) $basename = 'noname';
                     $cid = $basename . '.' . microtime(true) . $key . $ext;
 
                     $object['_attachments'][$cid] = $attachment;
                     unset($object['_attachments'][$key]);
                 }
             }
         }
 
         // save recurrence exceptions as individual objects due to lack of support in Kolab v2 format
         if (kolab_storage::$version == '2.0' && $object['recurrence']['EXCEPTIONS']) {
             $this->save_recurrence_exceptions($object, $type);
         }
 
         // check IMAP BINARY extension support for 'file' objects
         // allow configuration to workaround bug in Cyrus < 2.4.17
         $rcmail = rcube::get_instance();
         $binary = $type == 'file' && !$rcmail->config->get('kolab_binary_disable') && $this->imap->get_capability('BINARY');
 
         // generate and save object message
         if ($raw_msg = $this->build_message($object, $type, $binary, $body_file)) {
             // resolve old msguid before saving
             if ($uid && empty($object['_msguid']) && ($msguid = $this->cache->uid2msguid($uid))) {
                 $object['_msguid'] = $msguid;
                 $object['_mailbox'] = $this->name;
             }
 
             $result = $this->imap->save_message($this->name, $raw_msg, null, false, null, null, $binary);
 
             // update cache with new UID
             if ($result) {
                 $old_uid = $object['_msguid'];
 
                 $object['_msguid'] = $result;
                 $object['_mailbox'] = $this->name;
 
                 if ($old_uid) {
                     // delete old message
                     $this->cache->imap_mode(true);
                     $this->imap->delete_message($old_uid, $object['_mailbox']);
                     $this->cache->imap_mode(false);
                 }
 
                 // insert/update message in cache
                 $this->cache->save($result, $object, $old_uid);
             }
 
             // remove temp file
             if ($body_file) {
                 @unlink($body_file);
             }
         }
 
         return $result;
     }
 
     /**
      * Save recurrence exceptions as individual objects.
      * The Kolab v2 format doesn't allow us to save fully embedded exception objects.
      *
      * @param array Hash array with event properties
      * @param string Object type
      */
     private function save_recurrence_exceptions(&$object, $type = null)
     {
         if ($object['recurrence']['EXCEPTIONS']) {
             $exdates = [];
             foreach ((array) $object['recurrence']['EXDATE'] as $exdate) {
                 $key = $exdate instanceof DateTimeInterface ? $exdate->format('Y-m-d') : strval($exdate);
                 $exdates[$key] = 1;
             }
 
             // save every exception as individual object
             foreach ((array) $object['recurrence']['EXCEPTIONS'] as $exception) {
                 $exception['uid'] = self::recurrence_exception_uid($object['uid'], $exception['start']->format('Ymd'));
                 $exception['sequence'] = $object['sequence'] + 1;
 
                 if ($exception['thisandfuture']) {
                     $exception['recurrence'] = $object['recurrence'];
 
                     // adjust the recurrence duration of the exception
                     if ($object['recurrence']['COUNT']) {
                         $recurrence = new kolab_date_recurrence($object['_formatobj']);
                         if ($end = $recurrence->end()) {
                             unset($exception['recurrence']['COUNT']);
                             $exception['recurrence']['UNTIL'] = $end;
                         }
                     }
 
                     // set UNTIL date if we have a thisandfuture exception
                     $untildate = clone $exception['start'];
                     $untildate->sub(new DateInterval('P1D'));
                     $object['recurrence']['UNTIL'] = $untildate;
                     unset($object['recurrence']['COUNT']);
                 }
                 else {
                     if (!$exdates[$exception['start']->format('Y-m-d')])
                         $object['recurrence']['EXDATE'][] = clone $exception['start'];
                     unset($exception['recurrence']);
                 }
 
                 unset($exception['recurrence']['EXCEPTIONS'], $exception['_formatobj'], $exception['_msguid']);
                 $this->save($exception, $type, $exception['uid']);
             }
 
             unset($object['recurrence']['EXCEPTIONS']);
         }
     }
 
     /**
      * Generate an object UID with the given recurrence-ID in a way that it is
      * unique (the original UID is not a substring) but still recoverable.
      */
     private static function recurrence_exception_uid($uid, $recurrence_id)
     {
         $offset = -2;
         return substr($uid, 0, $offset) . '-' . $recurrence_id . '-' . substr($uid, $offset);
     }
 
     /**
      * Delete the specified object from this folder.
      *
      * @param  mixed   $object  The Kolab object to delete or object UID
      * @param  boolean $expunge Should the folder be expunged?
      *
      * @return boolean True if successful, false on error
      */
     public function delete($object, $expunge = true)
     {
         if (!$this->valid) {
             return false;
         }
 
         $msguid = is_array($object) ? $object['_msguid'] : $this->cache->uid2msguid($object);
         $success = false;
 
         $this->cache->imap_mode(true);
 
         if ($msguid && $expunge) {
             $success = $this->imap->delete_message($msguid, $this->name);
         }
         else if ($msguid) {
             $success = $this->imap->set_flag($msguid, 'DELETED', $this->name);
         }
 
         $this->cache->imap_mode(false);
 
         if ($success) {
             $this->cache->set($msguid, false);
         }
 
         return $success;
     }
 
     /**
      *
      */
     public function delete_all()
     {
         if (!$this->valid) {
             return false;
         }
 
         $this->cache->purge();
         $this->cache->imap_mode(true);
         $result = $this->imap->clear_folder($this->name);
         $this->cache->imap_mode(false);
 
         return $result;
     }
 
     /**
      * Restore a previously deleted object
      *
      * @param string Object UID
      * @return mixed Message UID on success, false on error
      */
     public function undelete($uid)
     {
         if (!$this->valid) {
             return false;
         }
 
         if ($msguid = $this->cache->uid2msguid($uid, true)) {
             $this->cache->imap_mode(true);
             $result = $this->imap->set_flag($msguid, 'UNDELETED', $this->name);
             $this->cache->imap_mode(false);
 
             if ($result) {
                 return $msguid;
             }
         }
 
         return false;
     }
 
     /**
      * Move a Kolab object message to another IMAP folder
      *
      * @param string Object UID
      * @param string IMAP folder to move object to
      * @return boolean True on success, false on failure
      */
     public function move($uid, $target_folder)
     {
         if (!$this->valid) {
             return false;
         }
 
         if (is_string($target_folder))
             $target_folder = kolab_storage::get_folder($target_folder);
 
         if ($msguid = $this->cache->uid2msguid($uid)) {
             $this->cache->imap_mode(true);
             $result = $this->imap->move_message($msguid, $target_folder->name, $this->name);
             $this->cache->imap_mode(false);
 
             if ($result) {
                 $new_uid = ($copyuid = $this->imap->conn->data['COPYUID']) ? $copyuid[1] : null;
                 $this->cache->move($msguid, $uid, $target_folder, $new_uid);
                 return true;
             }
             else {
                 rcube::raise_error(array(
                     'code' => 600, 'type' => 'php',
                     'file' => __FILE__, 'line' => __LINE__,
                     'message' => "Failed to move message $msguid to $target_folder: " . $this->imap->get_error_str(),
                 ), true);
             }
         }
 
         return false;
     }
 
     /**
      * Creates source of the configuration object message
      *
      * @param array  $object    The array that holds the data of the object.
      * @param string $type      The type of the kolab object.
      * @param bool   $binary    Enables use of binary encoding of attachment(s)
      * @param string $body_file Reference to filename of message body
      *
      * @return mixed Message as string or array with two elements
      *               (one for message file path, second for message headers)
      */
     private function build_message(&$object, $type, $binary, &$body_file)
     {
         // load old object to preserve data we don't understand/process
         if (is_object($object['_formatobj']))
             $format = $object['_formatobj'];
         else if ($object['_msguid'] && ($old = $this->cache->get($object['_msguid'], $type, $object['_mailbox'])))
             $format = $old['_formatobj'];
 
         // create new kolab_format instance
         if (!$format)
             $format = kolab_format::factory($type, kolab_storage::$version);
 
         if (PEAR::isError($format))
             return false;
 
         $format->set($object);
         $xml = $format->write(kolab_storage::$version);
         $object['uid'] = $format->uid;  // read UID from format
         $object['_formatobj'] = $format;
 
         if (empty($xml) || !$format->is_valid() || empty($object['uid'])) {
             return false;
         }
 
         $mime     = new Mail_mime("\r\n");
         $rcmail   = rcube::get_instance();
         $headers  = array();
         $files    = array();
         $part_id  = 1;
         $encoding = $binary ? 'binary' : 'base64';
 
         if ($user_email = $rcmail->get_user_email()) {
             $headers['From'] = $user_email;
             $headers['To'] = $user_email;
         }
         $headers['Date'] = date('r');
         $headers['X-Kolab-Type'] = kolab_format::KTYPE_PREFIX . $type;
         $headers['X-Kolab-Mime-Version'] = kolab_storage::$version;
         $headers['Subject'] = $object['uid'];
 //        $headers['Message-ID'] = $rcmail->gen_message_id();
         $headers['User-Agent'] = $rcmail->config->get('useragent');
 
         // Check if we have enough memory to handle the message in it
         // It's faster than using files, so we'll do this if we only can
         if (!empty($object['_attachments']) && ($mem_limit = parse_bytes(ini_get('memory_limit'))) > 0) {
             $memory = function_exists('memory_get_usage') ? memory_get_usage() : 16*1024*1024; // safe value: 16MB
 
             foreach ($object['_attachments'] as $attachment) {
                 $memory += $attachment['size'];
             }
 
             // 1.33 is for base64, we need at least 4x more memory than the message size
             if ($memory * ($binary ? 1 : 1.33) * 4 > $mem_limit) {
                 $marker   = '%%%~~~' . md5(microtime(true) . $memory) . '~~~%%%';
                 $is_file  = true;
                 $temp_dir = unslashify($rcmail->config->get('temp_dir'));
                 $mime->setParam('delay_file_io', true);
             }
         }
 
         $mime->headers($headers);
         $mime->setTXTBody("This is a Kolab Groupware object. "
             . "To view this object you will need an email client that understands the Kolab Groupware format. "
             . "For a list of such email clients please visit http://www.kolab.org/\n\n");
 
         $ctype = kolab_storage::$version == '2.0' ? $format->CTYPEv2 : $format->CTYPE;
         // Convert new lines to \r\n, to wrokaround "NO Message contains bare newlines"
         // when APPENDing from temp file
         $xml = preg_replace('/\r?\n/', "\r\n", $xml);
 
         $mime->addAttachment($xml,  // file
             $ctype,                 // content-type
             'kolab.xml',            // filename
             false,                  // is_file
             '8bit',                 // encoding
             'attachment',           // disposition
             RCUBE_CHARSET           // charset
         );
         $part_id++;
 
         // save object attachments as separate parts
         foreach ((array)$object['_attachments'] as $key => $att) {
             if (empty($att['content']) && !empty($att['id'])) {
                 // @TODO: use IMAP CATENATE to skip attachment fetch+push operation
                 $msguid = $object['_copyfrom'] ?: ($object['_msguid'] ?: $object['uid']);
                 if ($is_file) {
                     $att['path'] = tempnam($temp_dir, 'rcmAttmnt');
                     if (($fp = fopen($att['path'], 'w')) && $this->get_attachment($msguid, $att['id'], $object['_mailbox'], false, $fp, true)) {
                         fclose($fp);
                     }
                     else {
                         return false;
                     }
                 }
                 else {
                     $att['content'] = $this->get_attachment($msguid, $att['id'], $object['_mailbox'], false, null, true);
                 }
             }
 
             $headers = array('Content-ID' => Mail_mimePart::encodeHeader('Content-ID', '<' . $key . '>', RCUBE_CHARSET, 'quoted-printable'));
             $name = !empty($att['name']) ? $att['name'] : $key;
 
             // To store binary files we can use faster method
             // without writting full message content to a temporary file but
             // directly to IMAP, see rcube_imap_generic::append().
             // I.e. use file handles where possible
             if (!empty($att['path'])) {
                 if ($is_file && $binary) {
                     $files[] = fopen($att['path'], 'r');
                     $mime->addAttachment($marker, $att['mimetype'], $name, false, $encoding, 'attachment', '', '', '', null, null, '', RCUBE_CHARSET, $headers);
                 }
                 else {
                     $mime->addAttachment($att['path'], $att['mimetype'], $name, true, $encoding, 'attachment', '', '', '', null, null, '', RCUBE_CHARSET, $headers);
                 }
             }
             else {
                 if (is_resource($att['content']) && $is_file && $binary) {
                     $files[] = $att['content'];
                     $mime->addAttachment($marker, $att['mimetype'], $name, false, $encoding, 'attachment', '', '', '', null, null, '', RCUBE_CHARSET, $headers);
                 }
                 else {
                     if (is_resource($att['content'])) {
                         @rewind($att['content']);
                         $att['content'] = stream_get_contents($att['content']);
                     }
                     $mime->addAttachment($att['content'], $att['mimetype'], $name, false, $encoding, 'attachment', '', '', '', null, null, '', RCUBE_CHARSET, $headers);
                 }
             }
 
             $object['_attachments'][$key]['id'] = ++$part_id;
         }
 
         if (!$is_file || !empty($files)) {
             $message = $mime->getMessage();
         }
 
         // parse message and build message array with
         // attachment file pointers in place of file markers
         if (!empty($files)) {
             $message = explode($marker, $message);
             $tmp     = array();
 
             foreach ($message as $msg_part) {
                 $tmp[] = $msg_part;
                 if ($file = array_shift($files)) {
                     $tmp[] = $file;
                 }
             }
             $message = $tmp;
         }
         // write complete message body into temp file
         else if ($is_file) {
             // use common temp dir
             $body_file = tempnam($temp_dir, 'rcmMsg');
 
             if (PEAR::isError($mime_result = $mime->saveMessageBody($body_file))) {
                 rcube::raise_error(array('code' => 650, 'type' => 'php',
                     'file' => __FILE__, 'line' => __LINE__,
                     'message' => "Could not create message: ".$mime_result->getMessage()),
                     true, false);
                 return false;
             }
 
             $message = array(trim($mime->txtHeaders()) . "\r\n\r\n", fopen($body_file, 'r'));
         }
 
         return $message;
     }
 
     /**
      * Triggers any required updates after changes within the
      * folder. This is currently only required for handling free/busy
      * information with Kolab.
      *
      * @return boolean|PEAR_Error True if successfull.
      */
     public function trigger()
     {
         $owner = $this->get_owner();
         $result = false;
 
         switch($this->type) {
         case 'event':
             if ($this->get_namespace() == 'personal') {
                 $result = $this->trigger_url(
                     sprintf('%s/trigger/%s/%s.pfb',
                         kolab_storage::get_freebusy_server(),
                         urlencode($owner),
                         urlencode($this->imap->mod_folder($this->name))
                     ),
                     $this->imap->options['user'],
                     $this->imap->options['password']
                 );
             }
             break;
 
         default:
             return true;
         }
 
         if ($result && is_object($result) && is_a($result, 'PEAR_Error')) {
             return PEAR::raiseError(
                 sprintf("Failed triggering folder %s. Error was: %s", $this->name, $result->getMessage())
             );
         }
 
         return $result;
     }
 
     /**
      * Triggers a URL.
      *
      * @param string $url          The URL to be triggered.
      * @param string $auth_user    Username to authenticate with
      * @param string $auth_passwd  Password for basic auth
      * @return boolean|PEAR_Error  True if successfull.
      */
     private function trigger_url($url, $auth_user = null, $auth_passwd = null)
     {
         try {
             $request = libkolab::http_request($url);
 
             // set authentication credentials
             if ($auth_user && $auth_passwd)
                 $request->setAuth($auth_user, $auth_passwd);
 
             $result = $request->send();
             // rcube::write_log('trigger', $result->getBody());
         }
         catch (Exception $e) {
             return PEAR::raiseError($e->getMessage());
         }
 
         return true;
     }
 
     /**
      * Log content to a file in per_user_loggin dir if configured
      */
     private static function save_user_xml($filename, $content)
     {
         $rcmail = rcube::get_instance();
 
         if ($rcmail->config->get('kolab_format_error_log')) {
             $log_dir   = $rcmail->config->get('log_dir', RCUBE_INSTALL_PATH . 'logs');
             $user_name = $rcmail->get_user_name();
             $log_dir   = $log_dir . '/' . $user_name;
 
             if (!empty($user_name) && is_writable($log_dir)) {
                 file_put_contents("$log_dir/$filename", $content);
             }
         }
     }
 }
diff --git a/plugins/libkolab/lib/kolab_storage_folder_api.php b/plugins/libkolab/lib/kolab_storage_folder_api.php
index 1879d6b9..c1cfd5d6 100644
--- a/plugins/libkolab/lib/kolab_storage_folder_api.php
+++ b/plugins/libkolab/lib/kolab_storage_folder_api.php
@@ -1,379 +1,379 @@
 <?php
 
 /**
  * Abstract interface class for Kolab storage IMAP folder objects
  *
  * @author Thomas Bruederli <bruederli@kolabsys.com>
  *
  * Copyright (C) 2014, Kolab Systems AG <contact@kolabsys.com>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
  * published by the Free Software Foundation, either version 3 of the
  * License, or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU Affero General Public License for more details.
  *
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 abstract class kolab_storage_folder_api
 {
     /**
      * Folder identifier
      * @var string
      */
     public $id;
 
     /**
      * The folder name.
      * @var string
      */
     public $name;
 
     /**
      * The type of this folder.
      * @var string
      */
     public $type;
 
     /**
      * The subtype of this folder.
      * @var string
      */
     public $subtype;
 
     /**
      * Is this folder set to be the default for its type
      * @var boolean
      */
     public $default = false;
 
     /**
      * List of direct child folders
      * @var array
      */
     public $children = array();
 
     /**
      * Name of the parent folder
      * @var string
      */
     public $parent = '';
 
     protected $imap;
     protected $owner;
     protected $info;
     protected $idata;
     protected $namespace;
     protected $metadata;
 
 
     /**
      * Private constructor
      */
     protected function __construct($name)
     {
       $this->name = $name;
       $this->id   = kolab_storage::folder_id($name);
       $this->imap = rcube::get_instance()->get_storage();
     }
 
 
     /**
      * Returns the owner of the folder.
      *
      * @param boolean  Return a fully qualified owner name (i.e. including domain for shared folders)
      * @return string  The owner of this folder.
      */
     public function get_owner($fully_qualified = false)
     {
         // return cached value
         if (isset($this->owner))
             return $this->owner;
 
         $info = $this->get_folder_info();
         $rcmail = rcube::get_instance();
 
         switch ($info['namespace']) {
         case 'personal':
             $this->owner = $rcmail->get_user_name();
             break;
 
         case 'shared':
             $this->owner = 'anonymous';
             break;
 
         default:
             list($prefix, $this->owner) = explode($this->imap->get_hierarchy_delimiter(), $info['name']);
             $fully_qualified = true;  // enforce email addresses (backwards compatibility)
             break;
         }
 
         if ($fully_qualified && strpos($this->owner, '@') === false) {
             // extract domain from current user name
             $domain = strstr($rcmail->get_user_name(), '@');
             // fall back to mail_domain config option
             if (empty($domain) && ($mdomain = $rcmail->config->mail_domain($this->imap->options['host']))) {
                 $domain = '@' . $mdomain;
             }
             $this->owner .= $domain;
         }
 
         return $this->owner;
     }
 
 
     /**
      * Getter for the name of the namespace to which the IMAP folder belongs
      *
      * @return string Name of the namespace (personal, other, shared)
      */
     public function get_namespace()
     {
         if (!isset($this->namespace))
             $this->namespace = $this->imap->folder_namespace($this->name);
 
         return $this->namespace;
     }
 
     /**
      * Get the display name value of this folder
      *
      * @return string Folder name
      */
     public function get_name()
     {
         return kolab_storage::object_name($this->name);
     }
 
     /**
      * Getter for the top-end folder name (not the entire path)
      *
      * @return string Name of this folder
      */
     public function get_foldername()
     {
         $parts = explode($this->imap->get_hierarchy_delimiter(), $this->name);
 
         return rcube_charset::convert(end($parts), 'UTF7-IMAP');
     }
 
     /**
      * Getter for parent folder path
      *
      * @return string Full path to parent folder
      */
     public function get_parent()
     {
         $delim = $this->imap->get_hierarchy_delimiter();
         $path  = explode($delim, $this->name);
 
         array_pop($path);
 
         // don't list top-level namespace folder
         if (count($path) == 1 && in_array($this->get_namespace(), array('other', 'shared'))) {
             $path = array();
         }
 
         return join($delim, $path);
     }
 
     /**
      * Getter for the Cyrus mailbox identifier corresponding to this folder
      * (e.g. user/john.doe/Calendar/Personal@example.org)
      *
      * @return string Mailbox ID
      */
     public function get_mailbox_id()
     {
         $info = $this->get_folder_info();
         $owner = $this->get_owner();
         list($user, $domain) = explode('@', $owner);
 
         switch ($info['namespace']) {
         case 'personal':
             return sprintf('user/%s/%s@%s', $user, $this->name, $domain);
 
         case 'shared':
             $ns = $this->imap->get_namespace('shared');
             $prefix = is_array($ns) ? $ns[0][0] : '';
             list(, $domain) = explode('@', rcube::get_instance()->get_user_name());
             return substr($this->name, strlen($prefix)) . '@' . $domain;
 
         default:
             $ns = $this->imap->get_namespace('other');
             $prefix = is_array($ns) ? $ns[0][0] : '';
             list($user, $folder) = explode($this->imap->get_hierarchy_delimiter(), substr($info['name'], strlen($prefix)), 2);
             if (strpos($user, '@')) {
                 list($user, $domain) = explode('@', $user);
             }
             return sprintf('user/%s/%s@%s', $user, $folder, $domain);
         }
     }
 
     /**
      * Get the color value stored in metadata
      *
      * @param string Default color value to return if not set
      * @return mixed Color value from IMAP metadata or $default is not set
      */
     public function get_color($default = null)
     {
         // color is defined in folder METADATA
         $metadata = $this->get_metadata();
-        if (($color = $metadata[kolab_storage::COLOR_KEY_PRIVATE]) || ($color = $metadata[kolab_storage::COLOR_KEY_SHARED])) {
+        if (($color = $metadata[kolab_storage::COLOR_KEY_PRIVATE] ?? null) || ($color = $metadata[kolab_storage::COLOR_KEY_SHARED] ?? null)) {
             return $color;
         }
 
         return $default;
     }
 
     /**
      * Returns IMAP metadata/annotations (GETMETADATA/GETANNOTATION)
      * supported by kolab_storage
      *
      * @return array Metadata entry-value hash array on success, NULL on error
      */
     public function get_metadata()
     {
         if ($this->metadata === null) {
             $this->metadata = kolab_storage::folder_metadata($this->name);
         }
 
         return $this->metadata;
     }
 
     /**
      * Sets IMAP metadata/annotations (SETMETADATA/SETANNOTATION)
      *
      * @param array  $entries Entry-value array (use NULL value as NIL)
      * @return boolean True on success, False on failure
      */
     public function set_metadata($entries)
     {
         $this->metadata = null;
         return $this->imap->set_metadata($this->name, $entries);
     }
 
     /**
      *
      */
     public function get_folder_info()
     {
         if (!isset($this->info))
             $this->info = $this->imap->folder_info($this->name);
 
         return $this->info;
     }
 
     /**
      * Make IMAP folder data available for this folder
      */
     public function get_imap_data()
     {
         if (!isset($this->idata))
             $this->idata = $this->imap->folder_data($this->name);
 
         return $this->idata;
     }
 
     /**
      * Returns (full) type of IMAP folder
      *
      * @return string Folder type
      */
     public function get_type()
     {
         $metadata = $this->get_metadata();
 
         if (!empty($metadata)) {
             return kolab_storage::folder_select_metadata($metadata);
         }
 
         return $this->type;
     }
 
     /**
      * Get IMAP ACL information for this folder
      *
      * @return string  Permissions as string
      */
     public function get_myrights()
     {
         $rights = $this->info['rights'];
 
         if (!is_array($rights))
             $rights = $this->imap->my_rights($this->name);
 
         return join('', (array)$rights);
     }
 
     /**
      * Helper method to extract folder UID metadata
      *
      * @return string Folder's UID
      */
     public function get_uid()
     {
         // To be implemented by extending classes
         return false;
     }
 
     /**
      * Check activation status of this folder
      *
      * @return boolean True if enabled, false if not
      */
     public function is_active()
     {
         return kolab_storage::folder_is_active($this->name);
     }
 
     /**
      * Change activation status of this folder
      *
      * @param boolean The desired subscription status: true = active, false = not active
      *
      * @return True on success, false on error
      */
     public function activate($active)
     {
         return $active ? kolab_storage::folder_activate($this->name) : kolab_storage::folder_deactivate($this->name);
     }
 
     /**
      * Check subscription status of this folder
      *
      * @return boolean True if subscribed, false if not
      */
     public function is_subscribed()
     {
         return kolab_storage::folder_is_subscribed($this->name);
     }
 
     /**
      * Change subscription status of this folder
      *
      * @param boolean The desired subscription status: true = subscribed, false = not subscribed
      *
      * @return True on success, false on error
      */
     public function subscribe($subscribed)
     {
         return $subscribed ? kolab_storage::folder_subscribe($this->name) : kolab_storage::folder_unsubscribe($this->name);
     }
 
     /**
      * Return folder name as string representation of this object
      *
      * @return string Full IMAP folder name
      */
     public function __toString()
     {
         return $this->name;
     }
 }
diff --git a/plugins/libkolab/lib/kolab_storage_folder_virtual.php b/plugins/libkolab/lib/kolab_storage_folder_virtual.php
index bf3ba554..8c6b3319 100644
--- a/plugins/libkolab/lib/kolab_storage_folder_virtual.php
+++ b/plugins/libkolab/lib/kolab_storage_folder_virtual.php
@@ -1,59 +1,58 @@
 <?php
 
 /**
  * Helper class that represents a virtual IMAP folder
  * with a subset of the kolab_storage_folder API.
  *
  * @author Thomas Bruederli <bruederli@kolabsys.com>
  *
  * Copyright (C) 2014, Kolab Systems AG <contact@kolabsys.com>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
  * published by the Free Software Foundation, either version 3 of the
  * License, or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU Affero General Public License for more details.
  *
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 class kolab_storage_folder_virtual extends kolab_storage_folder_api
 {
-    public $virtual = true;
-
     protected $displayname;
 
     public function __construct($name, $dispname, $ns, $parent = '')
     {
         parent::__construct($name);
 
         $this->namespace = $ns;
         $this->parent    = $parent;
         $this->displayname = $dispname;
+        $this->virtual = true;
     }
 
     /**
      * Get the display name value of this folder
      *
      * @return string Folder name
      */
     public function get_name()
     {
         return $this->displayname ?: parent::get_name();
     }
 
     /**
      * Get the color value stored in metadata
      *
      * @param string Default color value to return if not set
      * @return mixed Color value from IMAP metadata or $default is not set
      */
     public function get_color($default = null)
     {
         return $default;
     }
 }
diff --git a/plugins/libkolab/libkolab.php b/plugins/libkolab/libkolab.php
index eb5b1c10..e888196a 100644
--- a/plugins/libkolab/libkolab.php
+++ b/plugins/libkolab/libkolab.php
@@ -1,392 +1,392 @@
 <?php
 
 /**
  * Kolab core library
  *
  * Plugin to setup a basic environment for the interaction with a Kolab server.
  * Other Kolab-related plugins will depend on it and can use the library classes
  *
  * @version @package_version@
  * @author Thomas Bruederli <bruederli@kolabsys.com>
  *
  * Copyright (C) 2012-2015, Kolab Systems AG <contact@kolabsys.com>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
  * published by the Free Software Foundation, either version 3 of the
  * License, or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU Affero General Public License for more details.
  *
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
 class libkolab extends rcube_plugin
 {
     static $http_requests = array();
     static $bonnie_api    = false;
 
     /**
      * Required startup method of a Roundcube plugin
      */
     public function init()
     {
         // load local config
         $this->load_config();
         $this->require_plugin('libcalendaring');
 
         // extend include path to load bundled lib classes
         $include_path = $this->home . '/lib' . PATH_SEPARATOR . ini_get('include_path');
         set_include_path($include_path);
 
         $this->add_hook('storage_init', array($this, 'storage_init'));
         $this->add_hook('storage_connect', array($this, 'storage_connect'));
         $this->add_hook('user_delete', array('kolab_storage', 'delete_user_folders'));
 
         // For Chwala
         $this->add_hook('folder_mod', array('kolab_storage', 'folder_mod'));
 
         $rcmail = rcube::get_instance();
         try {
             kolab_format::$timezone = new DateTimeZone($rcmail->config->get('timezone', 'GMT'));
         }
         catch (Exception $e) {
             rcube::raise_error($e, true);
             kolab_format::$timezone = new DateTimeZone('GMT');
         }
 
         $this->add_texts('localization/', false);
 
         if (!empty($rcmail->output->type) && $rcmail->output->type == 'html') {
             $rcmail->output->add_handler('libkolab.folder_search_form', array($this, 'folder_search_form'));
             $this->include_stylesheet($this->local_skin_path() . '/libkolab.css');
         }
 
         // embed scripts and templates for email message audit trail
         if ($rcmail->task == 'mail' && self::get_bonnie_api()) {
             if ($rcmail->output->type == 'html') {
                 $this->add_hook('render_page', array($this, 'bonnie_render_page'));
                 $this->include_script('libkolab.js');
 
                 // add 'Show history' item to message menu
                 $this->api->add_content(html::tag('li', array('role' => 'menuitem'),
                     $this->api->output->button(array(
                         'command'  => 'kolab-mail-history',
                         'label'    => 'libkolab.showhistory',
                         'type'     => 'link',
                         'classact' => 'icon history active',
                         'class'    => 'icon history disabled',
                         'innerclass' => 'icon history',
                     ))),
                     'messagemenu');
             }
 
             $this->register_action('plugin.message-changelog', array($this, 'message_changelog'));
         }
     }
 
     /**
      * Hook into IMAP FETCH HEADER.FIELDS command and request Kolab-specific headers
      */
     function storage_init($p)
     {
         $kolab_headers = 'X-KOLAB-TYPE X-KOLAB-MIME-VERSION MESSAGE-ID';
 
         if (!empty($p['fetch_headers'])) {
             $p['fetch_headers'] .= ' ' . $kolab_headers;
         }
         else {
             $p['fetch_headers'] = $kolab_headers;
         }
 
         return $p;
     }
 
     /**
      * Hook into IMAP connection to replace client identity
      */
     function storage_connect($p)
     {
         $client_name = 'Roundcube/Kolab';
 
         if (empty($p['ident'])) {
             $p['ident'] = array(
                 'name'    => $client_name,
                 'version' => RCUBE_VERSION,
 /*
                 'php'     => PHP_VERSION,
                 'os'      => PHP_OS,
                 'command' => $_SERVER['REQUEST_URI'],
 */
             );
         }
         else {
             $p['ident']['name'] = $client_name;
         }
 
         return $p;
     }
 
     /**
      * Getter for a singleton instance of the Bonnie API
      *
      * @return mixed kolab_bonnie_api instance if configured, false otherwise
      */
     public static function get_bonnie_api()
     {
         // get configuration for the Bonnie API
         if (!self::$bonnie_api && ($bonnie_config = rcube::get_instance()->config->get('kolab_bonnie_api', false))) {
             self::$bonnie_api = new kolab_bonnie_api($bonnie_config);
         }
 
         return self::$bonnie_api;
     }
 
     /**
      * Hook to append the message history dialog template to the mail view
      */
     function bonnie_render_page($p)
     {
         if (($p['template'] === 'mail' || $p['template'] === 'message') && !$p['kolab-audittrail']) {
             // append a template for the audit trail dialog
             $this->api->output->add_footer(
                 html::div(array('id' => 'mailmessagehistory',  'class' => 'uidialog', 'aria-hidden' => 'true', 'style' => 'display:none'),
                     self::object_changelog_table(array('class' => 'records-table changelog-table'))
                 )
             );
             $this->api->output->set_env('kolab_audit_trail', true);
             $p['kolab-audittrail'] = true;
         }
 
         return $p;
     }
 
     /**
      * Handler for message audit trail changelog requests
      */
     public function message_changelog()
     {
         if (!self::$bonnie_api) {
             return false;
         }
 
         $rcmail = rcube::get_instance();
         $msguid = rcube_utils::get_input_value('_uid', rcube_utils::INPUT_POST, true);
         $mailbox = rcube_utils::get_input_value('_mbox', rcube_utils::INPUT_POST);
 
         $result = $msguid && $mailbox ? self::$bonnie_api->changelog('mail', null, $mailbox, $msguid) : null;
         if (is_array($result)) {
             if (is_array($result['changes'])) {
                 $dtformat = $rcmail->config->get('date_format') . ' ' . $rcmail->config->get('time_format');
                 array_walk($result['changes'], function(&$change) use ($dtformat, $rcmail) {
                   if ($change['date']) {
                       $dt = rcube_utils::anytodatetime($change['date']);
                       if ($dt instanceof DateTimeInterface) {
                           $change['date'] = $rcmail->format_date($dt, $dtformat);
                       }
                   }
                 });
             }
             $this->api->output->command('plugin.message_render_changelog', $result['changes']);
         }
         else {
             $this->api->output->command('plugin.message_render_changelog', false);
         }
 
         $this->api->output->send();
     }
 
     /**
      * Wrapper function to load and initalize the HTTP_Request2 Object
      *
      * @param string|Net_Url2 Request URL
      * @param string          Request method ('OPTIONS','GET','HEAD','POST','PUT','DELETE','TRACE','CONNECT')
      * @param array           Configuration for this Request instance, that will be merged
      *                        with default configuration
      *
      * @return HTTP_Request2 Request object
      */
     public static function http_request($url = '', $method = 'GET', $config = array())
     {
         $rcube       = rcube::get_instance();
         $http_config = (array) $rcube->config->get('kolab_http_request');
 
         // deprecated configuration options
         if (empty($http_config)) {
             foreach (array('ssl_verify_peer', 'ssl_verify_host') as $option) {
                 $value = $rcube->config->get('kolab_' . $option, true);
                 if (is_bool($value)) {
                     $http_config[$option] = $value;
                 }
             }
         }
 
         if (!empty($config)) {
             $http_config = array_merge($http_config, $config);
         }
 
         // force CURL adapter, this allows to handle correctly
         // compressed responses with SplObserver registered (kolab_files) (#4507)
         $http_config['adapter'] = 'HTTP_Request2_Adapter_Curl';
 
         $key = md5(serialize($http_config));
 
         if (!empty(self::$http_requests[$key])) {
             $request = self::$http_requests[$key];
         }
         else {
             // load HTTP_Request2 (support both composer-installed and system-installed package)
             if (!class_exists('HTTP_Request2')) {
                 require_once 'HTTP/Request2.php';
             }
 
             try {
                 $request = new HTTP_Request2();
                 $request->setConfig($http_config);
             }
             catch (Exception $e) {
                 rcube::raise_error($e, true, true);
             }
 
             // proxy User-Agent string
             $request->setHeader('user-agent', $_SERVER['HTTP_USER_AGENT']);
 
             self::$http_requests[$key] = $request;
         }
 
         // cleanup
         try {
             $request->setBody('');
             $request->setUrl($url);
             $request->setMethod($method);
         }
         catch (Exception $e) {
             rcube::raise_error($e, true, true);
         }
 
         return $request;
     }
 
     /**
      * Table oultine for object changelog display
      */
     public static function object_changelog_table($attrib = array())
     {
         $rcube = rcube::get_instance();
         $attrib += array('domain' => 'libkolab');
 
         $table = new html_table(array('cols' => 5, 'border' => 0, 'cellspacing' => 0));
         $table->add_header('diff',      '');
         $table->add_header('revision',  $rcube->gettext('revision', $attrib['domain']));
         $table->add_header('date',      $rcube->gettext('date', $attrib['domain']));
         $table->add_header('user',      $rcube->gettext('user', $attrib['domain']));
         $table->add_header('operation', $rcube->gettext('operation', $attrib['domain']));
         $table->add_header('actions',   '&nbsp;');
 
         $rcube->output->add_label(
             'libkolab.showrevision',
             'libkolab.actionreceive',
             'libkolab.actionappend',
             'libkolab.actionmove',
             'libkolab.actiondelete',
             'libkolab.actionread',
             'libkolab.actionflagset',
             'libkolab.actionflagclear',
             'libkolab.objectchangelog',
             'libkolab.objectchangelognotavailable',
             'close'
         );
 
         return $table->show($attrib);
     }
 
     /**
      * Wrapper function for generating a html diff using the FineDiff class by Raymond Hill
      */
     public static function html_diff($from, $to, $is_html = null)
     {
         // auto-detect text/html format
         if ($is_html === null) {
             $from_html = (preg_match('/<(html|body)(\s+[a-z]|>)/', $from, $m) && strpos($from, '</'.$m[1].'>') > 0);
             $to_html   = (preg_match('/<(html|body)(\s+[a-z]|>)/', $to, $m) && strpos($to, '</'.$m[1].'>') > 0);
             $is_html   = $from_html || $to_html;
 
             // ensure both parts are of the same format
             if ($is_html && !$from_html) {
                 $converter = new rcube_text2html($from, false, array('wrap' => true));
                 $from = $converter->get_html();
             }
             if ($is_html && !$to_html) {
                 $converter = new rcube_text2html($to, false, array('wrap' => true));
                 $to = $converter->get_html();
             }
         }
 
         // compute diff from HTML
         if ($is_html) {
             include_once __dir__ . '/vendor/Caxy/HtmlDiff/Match.php';
             include_once __dir__ . '/vendor/Caxy/HtmlDiff/Operation.php';
             include_once __dir__ . '/vendor/Caxy/HtmlDiff/HtmlDiff.php';
 
             // replace data: urls with a transparent image to avoid memory problems
             $from = preg_replace('/src="data:image[^"]+/', 'src="data:image/gif;base64,R0lGODlhAQABAPAAAOjq6gAAACH/C1hNUCBEYXRhWE1QAT8AIfkEBQAAAAAsAAAAAAEAAQAAAgJEAQA7', $from);
             $to   = preg_replace('/src="data:image[^"]+/', 'src="data:image/gif;base64,R0lGODlhAQABAPAAAOjq6gAAACH/C1hNUCBEYXRhWE1QAT8AIfkEBQAAAAAsAAAAAAEAAQAAAgJEAQA7', $to);
 
             $diff = new Caxy\HtmlDiff\HtmlDiff($from, $to);
             $diffhtml = $diff->build();
 
             // remove empty inserts (from tables)
             return preg_replace('!<ins class="diff\w+">\s*</ins>!Uims', '', $diffhtml);
         }
         else {
             include_once __dir__ . '/vendor/finediff.php';
 
             $diff = new FineDiff($from, $to, FineDiff::$wordGranularity);
             return $diff->renderDiffToHTML();
         }
     }
 
     /**
      * Return a date() format string to render identifiers for recurrence instances
      *
      * @param array Hash array with event properties
      * @return string Format string
      */
     public static function recurrence_id_format($event)
     {
         return $event['allday'] ? 'Ymd' : 'Ymd\THis';
     }
 
     /**
      * Returns HTML code for folder search widget
      *
      * @param array $attrib Named parameters
      *
      * @return string HTML code for the gui object
      */
     public function folder_search_form($attrib)
     {
         $rcmail = rcube::get_instance();
         $attrib += array(
             'gui-object'    => false,
             'wrapper'       => true,
             'form-name'     => 'foldersearchform',
             'command'       => 'non-extsing-command',
             'reset-command' => 'non-existing-command',
         );
 
-        if ($attrib['label-domain'] && !strpos($attrib['buttontitle'], '.')) {
+        if (($attrib['label-domain'] ?? null) && !strpos($attrib['buttontitle'], '.')) {
             $attrib['buttontitle'] = $attrib['label-domain'] . '.' . $attrib['buttontitle'];
         }
 
         if ($attrib['buttontitle']) {
             $attrib['placeholder'] = $rcmail->gettext($attrib['buttontitle']);
         }
 
         return $rcmail->output->search_form($attrib);
     }
 }