diff --git a/public_html/js/files_api.js b/public_html/js/files_api.js
index eced24a..8efbb47 100644
--- a/public_html/js/files_api.js
+++ b/public_html/js/files_api.js
@@ -1,1045 +1,1046 @@
 /**
  +--------------------------------------------------------------------------+
  | This file is part of the Kolab File API                                  |
  |                                                                          |
  | Copyright (C) 2012-2015, Kolab Systems AG                                |
  |                                                                          |
  | 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/>      |
  +--------------------------------------------------------------------------+
  | Author: Aleksander Machniak <machniak@kolabsys.com>                      |
  +--------------------------------------------------------------------------+
 */
 
 function files_api()
 {
   var ref = this;
 
   // default config
   this.sessions = {};
   this.translations = {};
   this.env = {
     url: 'api/',
     directory_separator: '/',
     resources_dir: 'resources'
   };
 
 
   /*********************************************************/
   /*********          Basic utilities              *********/
   /*********************************************************/
 
   // set environment variable(s)
   this.set_env = function(p, value)
   {
     if (p != null && typeof p === 'object' && !value)
       for (var n in p)
         this.env[n] = p[n];
     else
       this.env[p] = value;
   };
 
   // add a localized label(s) to the client environment
   this.tdef = function(p, value)
   {
     if (typeof p == 'string')
       this.translations[p] = value;
     else if (typeof p == 'object')
       $.extend(this.translations, p);
   };
 
   // return a localized string
   this.t = function(label)
   {
     if (this.translations[label])
       return this.translations[label];
     else
       return label;
   };
 
   // print a message into browser console
   this.log = function(msg)
   {
     if (window.console && console.log)
       console.log(msg);
   };
 
   /********************************************************/
   /*********        Remote request methods        *********/
   /********************************************************/
 
   // send a http POST request to the API service
   this.post = function(action, data, func)
   {
     var url = this.env.url + '?method=' + action;
 
     if (!func) func = 'response';
 
     this.set_request_time();
 
     return $.ajax({
       type: 'POST', url: url, data: JSON.stringify(data), dataType: 'json',
       contentType: 'application/json; charset=utf-8',
       success: function(response) { if (typeof func == 'function') func(response); else ref[func](response); },
       error: function(o, status, err) { ref.http_error(o, status, err); },
       cache: false,
       beforeSend: function(xmlhttp) { xmlhttp.setRequestHeader('X-Session-Token', ref.env.token); }
     });
   };
 
   // send a http GET request to the API service
   this.get = function(action, data, func)
   {
     var url = this.env.url;
 
     if (!func) func = 'response';
 
     this.set_request_time();
     data.method = action;
 
     return $.ajax({
       type: 'GET', url: url, data: data, dataType: 'json',
       success: function(response) { if (typeof func == 'function') func(response); else ref[func](response); },
       error: function(o, status, err) { ref.http_error(o, status, err); },
       cache: false,
       beforeSend: function(xmlhttp) { xmlhttp.setRequestHeader('X-Session-Token', ref.env.token); }
     });
   };
 
   // send request with auto-selection of POST/GET method
   this.request = function(action, data, func)
   {
     // Use POST for modification actions with probable big request size
     var method = /_(create|delete|move|copy|update|auth|subscribe|unsubscribe|invite|decline|request|accept|remove)$/.test(action) ? 'post' : 'get';
     return this[method](action, data, func);
   };
 
   // handle HTTP request errors
   this.http_error = function(request, status, err)
   {
     var errmsg = request.statusText;
 
     this.set_busy(false);
     request.abort();
 
     if (request.status && errmsg)
       this.display_message(this.t('servererror') + ' (' + errmsg + ')', 'error');
   };
 
   this.response = function(response)
   {
     this.update_request_time();
     this.set_busy(false);
 
     return this.response_parse(response);
   };
 
   this.response_parse = function(response)
   {
     if (!response || response.status != 'OK') {
       // Logout on invalid-session error
       if (response && response.code == 403)
         this.logout(response);
       else
         this.display_message(response && response.reason ? response.reason : this.t('servererror'), 'error');
 
       return false;
     }
 
     return true;
   };
 
 
   /*********************************************************/
   /*********             Utilities                 *********/
   /*********************************************************/
 
   // Called on "session expired" session
   this.logout = function(response) {};
 
   // set state
   this.set_busy = function(state, message) {};
 
   // displays error message
   this.display_message = function(label, type) {};
 
   // called when a request timed out
   this.request_timed_out = function() {};
 
   // called on start of the request
   this.set_request_time = function() {};
 
   // called on request response
   this.update_request_time = function() {};
 
 
   /*********************************************************/
   /*********             Helpers                   *********/
   /*********************************************************/
 
   // compose a valid url with the given parameters
   this.url = function(action, query)
   {
     var k, param = {},
       querystring = typeof query === 'string' ? '&' + query : '';
 
     if (typeof action !== 'string')
       query = action;
     else if (!query || typeof query !== 'object')
       query = {};
 
     // overwrite task name
     if (action)
       query.method = action;
 
     // remove undefined values
     for (k in query) {
       if (query[k] !== undefined && query[k] !== null)
         param[k] = query[k];
     }
 
     return '?' + $.param(param) + querystring;
   };
 
   // fill folder selector with options
   this.folder_select_element = function(select, params)
   {
     var options = [],
       selected = params && params.selected ? params.selected : this.env.folder;
 
     if (params && params.empty)
       options.push($('<option>').val('').text('---'));
 
     $.each(this.env.folders, function(i, f) {
       var n, name = escapeHTML(f.name);
 
       // skip read-only folders
       if (params && params.writable && (f.readonly || f.virtual)) {
         var folder, found = false, prefix = i + ref.env.directory_separator;
 
         // for virtual folders check if there's any writable subfolder
         for (n in ref.env.folders) {
           if (n.indexOf(prefix) === 0) {
             folder = ref.env.folders[n];
             if (!folder.virtual && !folder.readonly) {
               found = true;
               break;
             }
           }
         }
 
         if (!found)
           return;
       }
 
       for (n=0; n<f.depth; n++)
         name = '&nbsp;&nbsp;&nbsp;' + name;
 
       options.push($('<option>').val(i).html(name));
     });
 
     select.empty().append(options);
 
     if (selected)
       select.val(selected);
   };
 
   // Folder list parser, converts it into structure
   this.folder_list_parse = function(list, num, subscribed)
   {
     var i, n, j, items, items_len, f, tmp, folder, readonly,
       subs_support, subs_prefixes = {}, found,
       separator = this.env.directory_separator,
       len = list ? list.length : 0, folders = {};
 
     if (!num) num = 1;
 
     if (subscribed === undefined)
       subscribed = true;
 
     // prepare subscriptions support detection
     if (len && this.env.caps) {
       subs_support = !!this.env.caps.SUBSCRIPTIONS;
       $.each(this.env.caps.MOUNTPOINTS || [], function(i, v) {
         subs_prefixes[i] = !!v.SUBSCRIPTIONS;
       });
     }
 
     for (i=0; i<len; i++) {
       folder = list[i];
       readonly = false;
 
       // in extended format folder is an object
       if (typeof folder !== 'string') {
         readonly = folder.readonly;
         folder = folder.folder;
       }
 
       items = folder.split(separator);
       items_len = items.length;
 
       for (n=0; n<items_len-1; n++) {
         tmp = items.slice(0, n+1);
         f = tmp.join(separator);
         if (!folders[f])
           folders[f] = {name: tmp.pop(), depth: n, id: 'f'+num++, virtual: 1};
       }
 
       folders[folder] = {
         name: items.pop(),
         depth: items_len-1,
         id: 'f' + num++,
         readonly: readonly
       };
 
       // set subscription flag, leave undefined if the source does not support subscriptions
       found = false;
       for (j in subs_prefixes) {
         if (folder === j) {
           // this is a mount point
           found = true;
           break;
         }
         if (folder.indexOf(j + separator) === 0) {
           if (subs_prefixes[j])
             folders[folder].subscribed = subscribed;
           found = true;
           break;
         }
       }
 
       if (!found && subs_support)
         folders[folder].subscribed = subscribed;
     }
 
     return folders;
   };
 
   // folder structure presentation (structure icons)
   this.folder_list_tree = function(folders)
   {
-    var i, n, diff, tree = [], folder;
+    var i, n, diff, prefix, tree = [], folder;
 
     for (i in folders) {
       items = i.split(this.env.directory_separator);
       items_len = items.length;
 
       // skip root
       if (items_len < 2) {
         tree = [];
         continue;
       }
 
       folders[i].tree = [1];
+      prefix = items.slice(0, items_len-1).join(this.env.directory_separator) + this.env.directory_separator;
 
       for (n=0; n<tree.length; n++) {
         folder = tree[n];
         diff = folders[folder].depth - (items_len - 1);
-        if (diff >= 0)
-          folders[folder].tree[diff] = folders[folder].tree[diff] ? folders[folder].tree[diff] + 2 : 2;
+        if (diff >= 0 && folder.indexOf(prefix) === 0)
+          folders[folder].tree[diff] |= 2;
       }
 
       tree.push(i);
     }
 
     for (i in folders) {
       if (tree = folders[i].tree) {
         var html = '', divs = [];
         for (n=0; n<folders[i].depth; n++) {
           if (tree[n] > 2)
             divs.push({'class': 'l3', width: 15});
           else if (tree[n] > 1)
             divs.push({'class': 'l2', width: 15});
           else if (tree[n] > 0)
             divs.push({'class': 'l1', width: 15});
           // separator
           else if (divs.length && !divs[divs.length-1]['class'])
             divs[divs.length-1].width += 15;
           else
             divs.push({'class': null, width: 15});
         }
 
         for (n=divs.length-1; n>=0; n--) {
           if (divs[n]['class'])
             html += '<span class="tree '+divs[n]['class']+'" />';
           else
             html += '<span style="width:'+divs[n].width+'px" />';
         }
 
         if (html)
           $('#' + folders[i].id + ' span.branch').html(html);
       }
     }
   };
 
   // Get editing sessions on the specified file
   this.file_sessions = function(file)
   {
     var sessions = [], folder = this.file_path(file);
 
     $.each(this.sessions[folder] || {}, function(session_id, session) {
       if (session.file == file) {
         session.id = session_id;
         sessions.push(session);
       }
     });
 
     return sessions;
   };
 
   // convert content-type string into class name
   this.file_type_class = function(type)
   {
     if (!type)
       return '';
 
     type = type.replace(/[^a-z0-9]/g, '_');
 
     return type;
   };
 
   // convert bytes into number with size unit
   this.file_size = function(size)
   {
     if (size >= 1073741824)
       return parseFloat(size/1073741824).toFixed(2) + ' GB';
     if (size >= 1048576)
       return parseFloat(size/1048576).toFixed(2) + ' MB';
     if (size >= 1024)
       return parseInt(size/1024) + ' kB';
 
     return parseInt(size || 0) + ' B';
   };
 
   // Extract file name from full path
   this.file_name = function(path)
   {
     var path = path.split(this.env.directory_separator);
     return path.pop();
   };
 
   // Extract file path from full path
   this.file_path = function(path)
   {
     var path = path.split(this.env.directory_separator);
     path.pop();
     return path.join(this.env.directory_separator);
   };
 
   // compare two sortable objects
   this.sort_compare = function(data1, data2)
   {
     var key = this.env.sort_col || 'name';
 
     if (key == 'mtime')
       key = 'modified';
 
     data1 = data1[key];
     data2 = data2[key];
 
     if (key == 'size' || key == 'modified')
       // numeric comparison
       return this.env.sort_reverse ? data2 - data1 : data1 - data2;
     else {
       // use Array.sort() for string comparison
       var arr = [data1, data2];
       arr.sort(function (a, b) {
         // @TODO: use localeCompare() arguments for better results
         return a.localeCompare(b);
       });
 
       if (this.env.sort_reverse)
         arr.reverse();
 
       return arr[0] === data2 ? 1 : -1;
     }
   };
 
   // Checks if specified mimetype is supported natively by the browser (return 1)
   // or can be displayed in the browser using File API viewer (return 2)
   // or using Manticore - WebODF collaborative editor (return 4)
   this.file_type_supported = function(type, capabilities)
   {
     var i, t, res = 0, regexps = [], img = 'jpg|jpeg|gif|bmp|png',
       caps = this.env.browser_capabilities || {},
       doc = /^application\/vnd.oasis.opendocument.(text)$/i;
 
     // Manticore?
     if (capabilities && capabilities.MANTICORE && doc.test(type))
       res |= 4;
 
     if (caps.tif)
       img += '|tiff';
 
     if ((new RegExp('^image/(' + img + ')$', 'i')).test(type))
       res |= 1;
 
     // prefer text viewer for any text type
     if (/^text\/(?!(pdf|x-pdf))/i.test(type))
       res |= 2;
 
     if (caps.pdf) {
       regexps.push(/^application\/(pdf|x-pdf|acrobat|vnd.pdf)/i);
       regexps.push(/^text\/(pdf|x-pdf)/i);
     }
 
     if (caps.flash)
       regexps.push(/^application\/x-shockwave-flash/i);
 
     for (i in regexps)
       if (regexps[i].test(type))
         res |= 1;
 
     for (i in navigator.mimeTypes) {
       t = navigator.mimeTypes[i].type;
       if (t == type && navigator.mimeTypes[i].enabledPlugin)
         res |= 1;
     }
 
     // types with viewer support
     if ($.inArray(type, this.env.supported_mimetypes) > -1)
       res |= 2;
 
     return res;
   };
 
   // Return browser capabilities
   this.browser_capabilities = function()
   {
     var i, caps = [], ctypes = ['pdf', 'flash', 'tif'];
 
     for (i in ctypes)
       if (this.env.browser_capabilities[ctypes[i]])
         caps.push(ctypes[i]);
 
     return caps;
   };
 
   // Checks browser capabilities eg. PDF support, TIF support
   this.browser_capabilities_check = function()
   {
     if (!this.env.browser_capabilities)
       this.env.browser_capabilities = {};
 
     if (this.env.browser_capabilities.pdf === undefined)
       this.env.browser_capabilities.pdf = this.pdf_support_check();
 
     if (this.env.browser_capabilities.flash === undefined)
       this.env.browser_capabilities.flash = this.flash_support_check();
 
     if (this.env.browser_capabilities.tif === undefined)
       this.tif_support_check();
   };
 
   this.tif_support_check = function()
   {
     var img = new Image(), ref = this;
 
     img.onload = function() { ref.env.browser_capabilities.tif = 1; };
     img.onerror = function() { ref.env.browser_capabilities.tif = 0; };
     img.src = this.env.resources_dir + '/blank.tif';
   };
 
   this.pdf_support_check = function()
   {
     var plugin = navigator.mimeTypes ? navigator.mimeTypes["application/pdf"] : {},
       plugins = navigator.plugins,
       len = plugins.length,
       regex = /Adobe Reader|PDF|Acrobat/i,
       ref = this;
 
     if (plugin && plugin.enabledPlugin)
         return 1;
 
     if (window.ActiveXObject) {
       try {
         if (axObj = new ActiveXObject("AcroPDF.PDF"))
           return 1;
       }
       catch (e) {}
       try {
         if (axObj = new ActiveXObject("PDF.PdfCtrl"))
           return 1;
       }
       catch (e) {}
     }
 
     for (i=0; i<len; i++) {
       plugin = plugins[i];
       if (typeof plugin === 'String') {
         if (regex.test(plugin))
           return 1;
       }
       else if (plugin.name && regex.test(plugin.name))
         return 1;
     }
 
     return 0;
   };
 
   this.flash_support_check = function()
   {
     var plugin = navigator.mimeTypes ? navigator.mimeTypes["application/x-shockwave-flash"] : {};
 
     if (plugin && plugin.enabledPlugin)
         return 1;
 
     if (window.ActiveXObject) {
       try {
         if (axObj = new ActiveXObject("ShockwaveFlash.ShockwaveFlash"))
           return 1;
       }
       catch (e) {}
     }
 
     return 0;
   };
 
   // converts number of seconds into HH:MM:SS format
   this.time_format = function(s)
   {
     s = parseInt(s);
 
     if (s >= 60*60*24)
       return '-';
 
     return (new Date(1970, 1, 1, 0, 0, s, 0)).toTimeString().replace(/.*(\d{2}:\d{2}:\d{2}).*/, '$1');
   };
 
   // same as str.split(delimiter) but it ignores delimiters within quoted strings
   this.explode_quoted_string = function(str, delimiter)
   {
     var result = [],
       strlen = str.length,
       q, p, i, chr, last;
 
     for (q = p = i = 0; i < strlen; i++) {
       chr = str.charAt(i);
       if (chr == '"' && last != '\\') {
         q = !q;
       }
       else if (!q && chr == delimiter) {
         result.push(str.substring(p, i));
         p = i + 1;
       }
       last = chr;
     }
 
     result.push(str.substr(p));
     return result;
   };
 };
 
 /**
  * Class implementing Manticore Client API
  *
  * Configuration:
  *    iframe - manticore iframe element
  *    title_input - document title element
  *    export_menu - export formats list
  *    members_list - collaborators list
  *    photo_url - <img> src for a collaborator
  *    photo_default_url - default image of a collaborator
  *
  *    set_busy, display_message, hide_message, gettext - common methods
  *
  *    api - Chwala files_api instance
  *    interval - how often to check for invitations in seconds (default: 60)
  *    owner - user identifier
  *    invitationMore - add "more" link into invitation notices
  *    invitationChange - method to handle invitation state updates
  */
 function manticore_api(conf)
 {
   var domain, manticore,
     locks = {},
     callbacks = {},
     members = {},
     self = this;
 
   // Sets state
   this.set_busy = function(state, message)
   {
     if (conf.set_busy)
       return conf.set_busy(state, message);
   };
 
   // Displays error/notification message
   this.display_message = function(label, type, is_txt, timeout)
   {
     if (conf.display_message)
       return conf.display_message(label, type, is_txt, timeout);
 
     if (type == 'error')
       alert(is_txt ? label : this.gettext(label));
   };
 
   // Hides the error/notification message
   this.hide_message = function(id)
   {
     if (conf.hide_message)
       return conf.hide_message(id);
   };
 
   // Localization method
   this.gettext = function(label)
   {
     if (conf.gettext)
       return conf.gettext(label);
 
     return label;
   };
 
   // Handle messages from Manticore
   this.message_handler = function(data)
   {
     var result;
 
     console.log(data);
 
     if (callbacks[data.id])
       result = callbacks[data.id](data);
     if (result !== false && data.name && conf[data.name])
       result = conf[data.name](data);
 
     delete callbacks[data.id];
 
     if (locks[data.id]) {
       this.set_busy(false);
       this.hide_message(data.id);
       delete locks[data.id];
     }
 
     if (result === false)
       return;
 
     switch (data.name) {
       case 'ready':
         this.ready();
         break;
 
       case 'titleChanged':
         if (conf.title_input)
           $(conf.title_input).val(data.value);
         break;
 
       case 'memberAdded':
         // @TODO: display notification?
         if (conf.members_list)
           $(conf.members_list).append(this.member_item(data));
         break;
 
       case 'memberRemoved':
         // @TODO: display notification?
         if (conf.members_list) {
           $('#' + members[data.memberId].id, conf.members_list).remove();
           delete members[data.memberId];
         }
         break;
     }
   };
 
   this.post = function(action, data, callback, lock_label)
   {
     if (!data) data = {};
 
     if (lock_label) {
       data.id = this.set_busy(true, this.gettext(lock_label));
       locks[data.id] = true;
     }
 
     if (!data.id)
       data.id = (new Date).getTime();
 
     // make sure the id is not in use
     while (callbacks[data.id])
       data.id++;
 
     data.name = action;
 
     callbacks[data.id] = callback;
 
     console.log(data);
 
     manticore.postMessage(data, domain);
   };
 
   this.ready = function()
   {
     if (this.init_lock) {
       this.set_busy(false);
       this.hide_message(this.init_lock);
       delete this.init_lock;
     }
 
     if (conf.export_menu)
       this.export_menu(conf.export_menu);
 
     if (conf.members_list)
       this.get_members(function(data) {
         var images = [], id = (new Date).getTime();
         $.each(data.value || [], function() {
           images.push(self.member_item(this, id++));
         });
         $(conf.members_list).html('').append(images);
       });
 
     if (conf.title_input)
       this.get_title(function(data) {
         $(conf.title_input).val(data.value);
       });
   };
 
   // Save current document
   this.save = function(callback)
   {
     this.post('actionSave', {}, callback, 'saving');
   };
 
   // Export/download current document
   this.export = function(type, callback)
   {
     this.post('actionExport', {value: type}, callback);
   };
 
   // Get supported export formats and create content of menu element
   this.export_menu = function(menu)
   {
     this.post('getExportFormats', {}, function(data) {
       var items = [];
 
       $.each(data.value || [], function(i, v) {
         items.push($('<li>').attr({role: 'menuitem'}).append(
           $('<a>').attr({href: '#', role: 'button', tabindex: 0, 'aria-disabled': false, 'class': 'active'})
             .text(v.label).click(function() { self.export(v.format); })
         ));
       });
 
       $(menu).html('').append(items);
     });
   };
 
   // Get document title
   this.get_title = function(callback)
   {
     this.post('getTitle', {}, callback);
   };
 
   // Set document title
   this.set_title = function(title, callback)
   {
     this.post('setTitle', {value: title}, callback);
   };
 
   // Get document session members
   this.get_members = function(callback)
   {
     this.post('getMembers', {}, callback);
   };
 
   // Creates session member image element
   this.member_item = function(member, id)
   {
     member.id = 'member' + (id || (new Date).getTime());
     member.name = member.fullName + ' (' + member.email + ')';
 
     members[member.memberId] = member;
 
     var img = $('<img>').attr({title: member.name, id: member.id, 'class': 'photo', src: conf.photo_default_url})
         .css({'border-color': member.color})
         .text(name);
 
     if (conf.photo_url) {
       img.attr('src', conf.photo_url.replace(/%email/, urlencode(member.email)));
       if (conf.photo_default_url)
         img.error(function() { this.src = conf.photo_default_url; });
     }
 
     return img;
   };
 
   // track changes in invitations
   this.track_invitations = function()
   {
     conf.api.request('invitations', {timestamp: this.invitations_timestamp || -1}, this.parse_invitations);
     this.invitations_timeout = setTimeout(function() { self.track_invitations(); }, (conf.interval || 60) * 1000);
   };
 
   // parse 'invitations' response
   this.parse_invitations = function(response)
   {
     if (!conf.api.response(response) || !response.result)
       return;
 
     var invitation_change = function(invitation) {
       var msg = self.invitation_msg(invitation);
 
       if (conf.invitationMore)
         msg = $('<div>')
           .append($('<span>').text(msg + ' '))
           .append($('<a>').text(self.gettext('more')).attr('id', invitation.id)).html();
 
       self.display_message(msg, 'notice', true, 30);
 
       if (conf.invitationChange)
         conf.invitationChange(invitation);
     }
 
     $.each(response.result.list || [], function(i, invitation) {
       invitation.id = 'i' + (response.result.timestamp + i);
       invitation.is_session_owner = invitation.user != conf.owner;
 
       // display notifications
       if (!invitation.is_session_owner) {
         if (invitation.status == 'invited' || invitation.status == 'declined-owner' || invitation.status == 'accepted-owner') {
           invitation_change(invitation);
         }
       }
       else {
         if (invitation.status == 'accepted' || invitation.status == 'declined' || invitation.status == 'requested') {
           invitation_change(invitation);
         }
       }
     });
 
     self.invitations_timestamp = response.result.timestamp;
   };
 
   this.invitation_msg = function(invitation)
   {
     return self.gettext(invitation.status.replace('-', '') + 'notice')
       .replace('$user', invitation.user_name ? invitation.user_name : invitation.user)
       .replace('$owner', invitation.owner_name ? invitation.owner_name : invitation.owner)
       .replace('$file', invitation.filename);
   };
 
   // Request access to the editing session
   this.invitation_request = function(invitation)
   {
     var params = {id: invitation.session_id, user: invitation.user || ''};
 
     conf.api.req = this.set_busy(true, 'invitationrequesting');
     conf.api.request('document_request', params, function(response) {
       self.invitation_response(response, invitation, 'requested');
     });
   };
 
   // Accept an invitations to the editing session
   this.invitation_accept = function(invitation)
   {
     var params = {id: invitation.session_id, user: invitation.user || ''};
 
     conf.api.req = this.set_busy(true, 'invitationaccepting');
     conf.api.request('document_accept', params, function(response) {
       self.invitation_response(response, invitation, 'accepted');
     });
   };
 
   // Decline an invitations to the editing session
   this.invitation_decline = function(invitation)
   {
     var params = {id: invitation.session_id, user: invitation.user || ''};
 
     conf.api.req = this.set_busy(true, 'invitationdeclining');
     conf.api.request('document_decline', params, function(response) {
       self.invitation_response(response, invitation, 'declined');
     });
   };
 
   // document_decline response handler
   this.invitation_response = function(response, invitation, status)
   {
     if (!conf.api.response(response))
       return;
 
     invitation.status = status;
 
     if (conf.invitationSaved)
       conf.invitationSaved(invitation);
   };
 
 
   if (!conf)
     conf = {};
 
   // Got Manticore iframe, use Client API
   if (conf.iframe) {
     manticore = conf.iframe.contentWindow;
 
     if (/^(https?:\/\/[^/]+)/i.test(conf.iframe.src))
       domain = RegExp.$1;
 
     // Register 'message' event to receive messages from Manticore iframe
     window.addEventListener('message', function(event) {
       if (event.source == manticore && event.origin == domain) {
         self.message_handler(event.data);
       }
     });
 
     // Bind for document title changes
     if (conf.title_input)
       $(conf.title_input).change(function() { self.set_title($(this).val()); });
 
     // Display loading message
     this.init_lock = this.set_busy(true, 'loading');
   }
 
   if (conf.api)
     this.track_invitations();
 };
 
 // Add escape() method to RegExp object
 // http://dev.rubyonrails.org/changeset/7271
 RegExp.escape = function(str)
 {
   return String(str).replace(/([.*+?^=!:${}()|[\]\/\\])/g, '\\$1');
 };
 
 // define String's startsWith() method for old browsers
 if (!String.prototype.startsWith) {
   String.prototype.startsWith = function(search, position) {
     position = position || 0;
     return this.slice(position, search.length) === search;
   };
 };
 
 // make a string URL safe (and compatible with PHP's rawurlencode())
 function urlencode(str)
 {
   if (window.encodeURIComponent)
     return encodeURIComponent(str).replace('*', '%2A');
 
   return escape(str)
     .replace('+', '%2B')
     .replace('*', '%2A')
     .replace('/', '%2F')
     .replace('@', '%40');
 };
 
 function escapeHTML(str)
 {
   return str === undefined ? '' : String(str)
     .replace(/&/g, '&amp;')
     .replace(/>/g, '&gt;')
     .replace(/</g, '&lt;');
 };
 
 function object_is_empty(obj)
 {
   if (obj)
     for (var i in obj)
       if (i !== null)
         return true;
 
   return false;
 }