diff --git a/plugins/kolab_delegation/kolab_delegation.php b/plugins/kolab_delegation/kolab_delegation.php
index 8596009e..c828093c 100644
--- a/plugins/kolab_delegation/kolab_delegation.php
+++ b/plugins/kolab_delegation/kolab_delegation.php
@@ -1,545 +1,547 @@
 <?php
 
 /**
  * Delegation configuration utility for Kolab accounts
  *
  * @version @package_version@
  * @author Aleksander Machniak <machniak@kolabsys.com>
  * @author Thomas Bruederli <bruederli@kolabsys.com>
  *
  * Copyright (C) 2011-2012, 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_delegation extends rcube_plugin
 {
     public $task = 'login|mail|settings|calendar';
 
     private $rc;
     private $engine;
 
 
     /**
      * Plugin initialization.
      */
     public function init()
     {
         $this->rc = rcube::get_instance();
 
         $this->require_plugin('libkolab');
         $this->require_plugin('kolab_auth');
 
         // on-login delegation initialization
         $this->add_hook('login_after', array($this, 'login_hook'));
         // on-check-recent delegation support
         $this->add_hook('check_recent', array($this, 'check_recent_hook'));
 
         // on-message-send delegation support
         $this->add_hook('message_before_send', array($this, 'message_before_send'));
 
         // delegation support in Calendar plugin
         $this->add_hook('message_load', array($this, 'message_load'));
         $this->add_hook('calendar_user_emails', array($this, 'calendar_user_emails'));
         $this->add_hook('calendar_list_filter', array($this, 'calendar_list_filter'));
         $this->add_hook('calendar_load_itip', array($this, 'calendar_load_itip'));
 
         // delegation support in kolab_auth plugin
         $this->add_hook('kolab_auth_emails', array($this, 'kolab_auth_emails'));
 
         if ($this->rc->task == 'settings') {
             // delegation management interface
             $this->register_action('plugin.delegation',              array($this, 'controller_ui'));
             $this->register_action('plugin.delegation-delete',       array($this, 'controller_action'));
             $this->register_action('plugin.delegation-save',         array($this, 'controller_action'));
             $this->register_action('plugin.delegation-autocomplete', array($this, 'controller_action'));
 
             $this->add_hook('settings_actions', array($this, 'settings_actions'));
 
             if ($this->rc->action == 'plugin.delegation' || empty($_REQUEST['_framed'])) {
                 $this->add_texts('localization/', array('deleteconfirm', 'savingdata', 'yes', 'no'));
 
                 if ($this->rc->action == 'plugin.delegation') {
                     $this->include_script('kolab_delegation.js');
                 }
 
                 $this->skin_path = $this->local_skin_path();
                 $this->include_stylesheet($this->skin_path . '/style.css');
             }
         }
         // Calendar plugin UI bindings
         else if ($this->rc->task == 'calendar' && empty($_REQUEST['_framed'])) {
-            $this->calendar_ui();
+            if ($this->rc->output->type == 'html') {
+                $this->calendar_ui();
+            }
         }
     }
 
     /**
      * Adds Delegation section in Settings
      */
     function settings_actions($args)
     {
         $args['actions'][] = array(
             'action' => 'plugin.delegation',
             'class'  => 'delegation',
             'label'  => 'tabtitle',
             'domain' => 'kolab_delegation',
             'title'  => 'delegationtitle',
         );
 
         return $args;
     }
 
     /**
      * Engine object getter
      */
     private function engine()
     {
         if (!$this->engine) {
             require_once $this->home . '/kolab_delegation_engine.php';
 
             $this->load_config();
             $this->engine = new kolab_delegation_engine();
         }
 
         return $this->engine;
     }
 
     /**
      * On-login action
      */
     public function login_hook($args)
     {
         // Manage (create) identities for delegator's email addresses
         // and subscribe to delegator's folders. Also remove identities
         // after delegation is removed
 
         $engine = $this->engine();
         $engine->delegation_init();
 
         return $args;
     }
 
     /**
      * Check-recent action
      */
     public function check_recent_hook($args)
     {
         // Checking for new messages shall be extended to Inbox folders of all
         // delegators if 'check_all_folders' is set to false.
 
         if ($this->rc->task != 'mail') {
             return $args;
         }
 
         if (!empty($args['all'])) {
             return $args;
         }
 
         if (empty($_SESSION['delegators'])) {
             return $args;
         }
 
         $storage  = $this->rc->get_storage();
         $other_ns = $storage->get_namespace('other');
         $folders  = $storage->list_folders_subscribed('', '*', 'mail');
 
         foreach (array_keys($_SESSION['delegators']) as $uid) {
             foreach ($other_ns as $ns) {
                 $folder = $ns[0] . $uid;
                 if (in_array($folder, $folders) && !in_array($folder, $args['folders'])) {
                     $args['folders'][] = $folder;
                 }
             }
         }
 
         return $args;
     }
 
     /**
      * Mail send action
      */
     public function message_before_send($args)
     {
         // Checking headers of email being send, we'll add
         // Sender: header if mail is send on behalf of someone else
 
         if (!empty($_SESSION['delegators'])) {
             $engine = $this->engine();
             $engine->delegator_delivery_filter($args);
         }
 
         return $args;
     }
 
     /**
      * E-mail message loading action
      */
     public function message_load($args)
     {
         // This is a place where we detect delegate context
         // So we can handle event invitations on behalf of delegator
         // @TODO: should we do this only in delegators' folders?
 
         // skip invalid messages or Kolab objects (for better performance)
         if (empty($args['object']->headers) || $args['object']->headers->get('x-kolab-type', false)) {
             return $args;
         }
 
         $engine = $this->engine();
         $context = $engine->delegator_context_from_message($args['object']);
 
         if ($context) {
             $this->rc->output->set_env('delegator_context', $context);
             $this->include_script('kolab_delegation.js');
         }
 
         return $args;
     }
 
     /**
      * calendar::get_user_emails() handler
      */
     public function calendar_user_emails($args)
     {
         // In delegator context we'll use delegator's addresses
         // instead of current user addresses
 
         if (!empty($_SESSION['delegators'])) {
             $engine = $this->engine();
             $engine->delegator_emails_filter($args);
         }
 
         return $args;
     }
 
     /**
      * calendar_driver::list_calendars() handler
      */
     public function calendar_list_filter($args)
     {
         // In delegator context we'll use delegator's folders
         // instead of current user folders
 
         if (!empty($_SESSION['delegators'])) {
             $engine = $this->engine();
             $engine->delegator_folder_filter($args);
         }
 
         return $args;
     }
 
     /**
      * calendar::load_itip() handler
      */
     public function calendar_load_itip($args)
     {
         // In delegator context we'll use delegator's address/name
         // for invitation responses
 
         if (!empty($_SESSION['delegators'])) {
             $engine = $this->engine();
             $engine->delegator_identity_filter($args);
         }
 
         return $args;
     }
 
     /**
      * Delegation support in Calendar plugin UI
      */
     public function calendar_ui()
     {
         // Initialize handling of delegators' identities in event form
 
         if (!empty($_SESSION['delegators'])) {
             $engine = $this->engine();
             $this->rc->output->set_env('namespace', $engine->namespace_js());
             $this->rc->output->set_env('delegators', $engine->list_delegators_js());
             $this->include_script('kolab_delegation.js');
         }
     }
 
     /**
      * Delegation support in kolab_auth plugin
      */
     public function kolab_auth_emails($args)
     {
         // Add delegators addresses to address selector in user identity form
 
         if (!empty($_SESSION['delegators'])) {
             // @TODO: Consider not adding all delegator addresses to the list.
             // Instead add only address of currently edited identity
             foreach ($_SESSION['delegators'] as $emails) {
                 $args['emails'] = array_merge($args['emails'], $emails);
             }
 
             $args['emails'] = array_unique($args['emails']);
             sort($args['emails']);
         }
 
         return $args;
     }
 
     /**
      * Delegation UI handler
      */
     public function controller_ui()
     {
         // main interface (delegates list)
         if (empty($_REQUEST['_framed'])) {
             $this->register_handler('plugin.delegatelist', array($this, 'delegate_list'));
 
             $this->rc->output->include_script('list.js');
             $this->rc->output->send('kolab_delegation.settings');
         }
         // delegate frame
         else {
             $this->register_handler('plugin.delegateform', array($this, 'delegate_form'));
             $this->register_handler('plugin.delegatefolders', array($this, 'delegate_folders'));
 
             $this->rc->output->set_env('autocomplete_max', (int)$this->rc->config->get('autocomplete_max', 15));
             $this->rc->output->set_env('autocomplete_min_length', $this->rc->config->get('autocomplete_min_length'));
             $this->rc->output->add_label('autocompletechars', 'autocompletemore');
 
             $this->rc->output->send('kolab_delegation.editform');
         }
     }
 
     /**
      * Delegation action handler
      */
     public function controller_action()
     {
         $this->add_texts('localization/');
 
         $engine = $this->engine();
 
         // Delegate delete
         if ($this->rc->action == 'plugin.delegation-delete') {
             $id      = rcube_utils::get_input_value('id', rcube_utils::INPUT_GPC);
             $success = $engine->delegate_delete($id, (bool) rcube_utils::get_input_value('acl', rcube_utils::INPUT_GPC));
 
             if ($success) {
                 $this->rc->output->show_message($this->gettext('deletesuccess'), 'confirmation');
                 $this->rc->output->command('plugin.delegate_save_complete', array('deleted' => $id));
             }
             else {
                 $this->rc->output->show_message($this->gettext('deleteerror'), 'error');
             }
         }
         // Delegate add/update
         else if ($this->rc->action == 'plugin.delegation-save') {
             $id  = rcube_utils::get_input_value('id', rcube_utils::INPUT_GPC);
             $acl = rcube_utils::get_input_value('folders', rcube_utils::INPUT_GPC);
 
             // update
             if ($id) {
                 $delegate = $engine->delegate_get($id);
                 $success  = $engine->delegate_acl_update($delegate['uid'], $acl);
 
                 if ($success) {
                     $this->rc->output->show_message($this->gettext('updatesuccess'), 'confirmation');
                     $this->rc->output->command('plugin.delegate_save_complete', array('updated' => $id));
                 }
                 else {
                     $this->rc->output->show_message($this->gettext('updateerror'), 'error');
                 }
             }
             // new
             else {
                 $login    = rcube_utils::get_input_value('newid', rcube_utils::INPUT_GPC);
                 $delegate = $engine->delegate_get_by_name($login);
                 $success  = $engine->delegate_add($delegate, $acl);
 
                 if ($success) {
                     $this->rc->output->show_message($this->gettext('createsuccess'), 'confirmation');
                     $this->rc->output->command('plugin.delegate_save_complete', array(
                         'created' => $delegate['ID'],
                         'name'    => $delegate['name'],
                     ));
                 }
                 else {
                     $this->rc->output->show_message($this->gettext('createerror'), 'error');
                 }
             }
         }
         // Delegate autocompletion
         else if ($this->rc->action == 'plugin.delegation-autocomplete') {
             $search = rcube_utils::get_input_value('_search', rcube_utils::INPUT_GPC, true);
             $reqid  = rcube_utils::get_input_value('_reqid', rcube_utils::INPUT_GPC);
             $users  = $engine->list_users($search);
 
             $this->rc->output->command('ksearch_query_results', $users, $search, $reqid);
         }
 
         $this->rc->output->send();
     }
 
     /**
      * Template object of delegates list
      */
     public function delegate_list($attrib = array())
     {
         $attrib += array('id' => 'delegate-list');
 
         $engine = $this->engine();
         $list   = $engine->list_delegates();
         $table  = new html_table();
 
         // sort delegates list
         asort($list, SORT_LOCALE_STRING);
 
         foreach ($list as $id => $delegate) {
             $table->add_row(array('id' => 'rcmrow' . $id));
             $table->add(null, Q($delegate));
         }
 
         $this->rc->output->add_gui_object('delegatelist', $attrib['id']);
         $this->rc->output->set_env('delegatecount', count($list));
 
         return $table->show($attrib);
     }
 
     /**
      * Template object of delegate form
      */
     public function delegate_form($attrib = array())
     {
         $engine   = $this->engine();
         $table    = new html_table(array('cols' => 2));
         $id       = rcube_utils::get_input_value('_id', rcube_utils::INPUT_GPC);
         $field_id = 'delegate';
 
         if ($id) {
             $delegate = $engine->delegate_get($id);
         }
 
         if ($delegate) {
             $input = new html_hiddenfield(array('name' => $field_id, 'id' => $field_id, 'size' => 40));
             $input = Q($delegate['name']) . $input->show($id);
 
             $this->rc->output->set_env('active_delegate', $id);
             $this->rc->output->command('parent.enable_command','delegate-delete', true);
         }
         else {
             $input = new html_inputfield(array('name' => $field_id, 'id' => $field_id, 'size' => 40));
             $input = $input->show();
         }
 
         $table->add('title', html::label($field_id, $this->gettext('delegate')));
         $table->add(null, $input);
 
         if ($attrib['form']) {
             $this->rc->output->add_gui_object('editform', $attrib['form']);
         }
 
         return $table->show($attrib);
     }
 
     /**
      * Template object of folders list
      */
     public function delegate_folders($attrib = array())
     {
         if (!$attrib['id']) {
             $attrib['id'] = 'delegatefolders';
         }
 
         $engine = $this->engine();
         $id     = rcube_utils::get_input_value('_id', rcube_utils::INPUT_GPC);
 
         if ($id) {
             $delegate = $engine->delegate_get($id);
         }
 
         $folder_data   = $engine->list_folders($delegate['uid']);
         $rights        = array();
         $folder_groups = array();
 
         foreach ($folder_data as $folder_name => $folder) {
             $folder_groups[$folder['type']][] = $folder_name;
             $rights[$folder_name] = $folder['rights'];
         }
 
         // build block for every folder type
         foreach ($folder_groups as $type => $group) {
             if (empty($group)) {
                 continue;
             }
             $attrib['type'] = $type;
             $html .= html::div('foldersblock',
                 html::tag('h3', $type, $this->gettext($type)) .
                     $this->delegate_folders_block($group, $attrib, $rights));
         }
 
         $this->rc->output->add_gui_object('folderslist', $attrib['id']);
 
         return html::div($attrib, $html);
     }
 
     /**
      * List of folders in specified group
      */
     private function delegate_folders_block($a_folders, $attrib, $rights)
     {
         $path      = 'plugins/kolab_delegation/' . $this->skin_path . '/';
         $read_ico  = $attrib['readicon'] ? html::img(array('src' =>  $path . $attrib['readicon'], 'title' => $this->gettext('read'))) : '';
         $write_ico = $attrib['writeicon'] ? html::img(array('src' => $path . $attrib['writeicon'], 'title' => $this->gettext('write'))) : '';
 
         $table = new html_table(array('cellspacing' => 0));
         $table->add_header(array('class' => 'read', 'title' => $this->gettext('read'), 'tabindex' => 0), $read_ico);
         $table->add_header(array('class' => 'write', 'title' => $this->gettext('write'), 'tabindex' => 0), $write_ico);
         $table->add_header('foldername', $this->rc->gettext('folder'));
 
         $checkbox_read  = new html_checkbox(array('name' => 'read[]', 'class' => 'read'));
         $checkbox_write = new html_checkbox(array('name' => 'write[]', 'class' => 'write'));
 
         $names = array();
         foreach ($a_folders as $folder) {
             $foldername = $origname = preg_replace('/^INBOX &raquo;\s+/', '', kolab_storage::object_name($folder));
 
             // find folder prefix to truncate (the same code as in kolab_addressbook plugin)
             for ($i = count($names)-1; $i >= 0; $i--) {
                 if (strpos($foldername, $names[$i].' &raquo; ') === 0) {
                     $length = strlen($names[$i].' &raquo; ');
                     $prefix = substr($foldername, 0, $length);
                     $count  = count(explode(' &raquo; ', $prefix));
                     $foldername = str_repeat('&nbsp;&nbsp;', $count-1) . '&raquo; ' . substr($foldername, $length);
                     break;
                 }
             }
 
             $folder_id = 'rcmf' . html_identifier($folder);
             $names[] = $origname;
             $classes = array('mailbox');
 
             if ($folder_class = $this->rc->folder_classname($folder)) {
                 $foldername = html::quote($this->rc->gettext($folder_class));
                 $classes[] = $folder_class;
             }
 
             $table->add_row();
             $table->add('read', $checkbox_read->show(
                 $rights[$folder] >= kolab_delegation_engine::ACL_READ ? $folder : null,
                 array('value' => $folder)));
             $table->add('write', $checkbox_write->show(
                 $rights[$folder] >= kolab_delegation_engine::ACL_WRITE ? $folder : null,
                 array('value' => $folder, 'id' => $folder_id)));
 
             $table->add(join(' ', $classes), html::label($folder_id, $foldername));
         }
 
         return $table->show();
     }
 }