diff --git a/plugins/calendar/calendar_ui.js b/plugins/calendar/calendar_ui.js
index 116b490e..2a8a8d2b 100644
--- a/plugins/calendar/calendar_ui.js
+++ b/plugins/calendar/calendar_ui.js
@@ -51,6 +51,7 @@ function rcube_calendar_ui(settings)
     var ignore_click = false;
     var event_defaults = { free_busy:'busy', alarms:'' };
     var event_attendees = [];
+    var calendars_list;
     var attendees_list;
     var resources_list;
     var resources_treelist;
@@ -2658,15 +2659,10 @@ function rcube_calendar_ui(settings)
     // mark the given calendar folder as selected
     this.select_calendar = function(id)
     {
-      var prefix = 'rcmlical';
-
-      $(rcmail.gui_objects.calendarslist).find('li.selected')
-        .removeClass('selected').addClass('unfocused');
-      $('#' + prefix + id, rcmail.gui_objects.calendarslist)
-        .removeClass('unfocused').addClass('selected');
+      calendars_list.select(id);
 
       // trigger event hook
-      rcmail.triggerEvent('selectfolder', { folder:name, prefix:prefix });
+      rcmail.triggerEvent('selectfolder', { folder:id, prefix:'rcmlical' });
 
       this.selected_calendar = id;
     };
@@ -2703,42 +2699,58 @@ function rcube_calendar_ui(settings)
         event_sources.push(this.calendars[id]);
       }
 
-      // init event handler on calendar list checkbox
-      if ((li = rcube_find_object('rcmlical' + id))) {
-        $('#'+li.id+' input').click(function(e){
-          var id = $(this).data('id');
-          if (me.calendars[id]) {  // add or remove event source on click
-            var action;
-            if (this.checked) {
-              action = 'addEventSource';
-              me.calendars[id].active = true;
-            }
-            else {
-              action = 'removeEventSource';
-              me.calendars[id].active = false;
-            }
-            
-            // add/remove event source
-            fc.fullCalendar(action, me.calendars[id]);
-            rcmail.http_post('calendar', { action:'subscribe', c:{ id:id, active:me.calendars[id].active?1:0 } });
-          }
-        }).data('id', id).get(0).checked = active;
-        
-        $(li).click(function(e){
-          me.select_calendar($(this).data('id'));
-          rcmail.enable_command('calendar-edit', true);
-          rcmail.enable_command('calendar-remove', 'calendar-showurl', true);
-        })
-        .dblclick(function(){ me.calendar_edit_dialog(me.calendars[me.selected_calendar]); })
-        .data('id', id);
-      }
-      
+      // check active calendars
+      $('#rcmlical'+id+' > .calendar input').data('id', id).get(0).checked = active;
+
       if (!cal.readonly && !this.selected_calendar) {
         this.selected_calendar = id;
         rcmail.enable_command('addevent', true);
       }
     }
-    
+
+    // initialize treelist widget that controls the calendars list
+    calendars_list = new rcube_treelist_widget(rcmail.gui_objects.calendarslist, {
+      id_prefix: 'rcmlical',
+      selectable: true,
+      searchbox: '#calendarlistsearch'
+    });
+    calendars_list.addEventListener('select', function(node){
+      me.select_calendar(node.id);
+      rcmail.enable_command('calendar-edit', 'calendar-showurl', true);
+      rcmail.enable_command('calendar-remove', !me.calendars[node.id].readonly);
+    });
+    calendars_list.addEventListener('search', function(search){
+      console.log(search);
+    });
+
+    // init (delegate) event handler on calendar list checkboxes
+    $(rcmail.gui_objects.calendarslist).on('click', 'input[type=checkbox]', function(e){
+      var id = $(this).data('id');
+      if (me.calendars[id]) {  // add or remove event source on click
+        var action;
+        if (this.checked) {
+          action = 'addEventSource';
+          me.calendars[id].active = true;
+        }
+        else {
+          action = 'removeEventSource';
+          me.calendars[id].active = false;
+        }
+
+        // add/remove event source
+        fc.fullCalendar(action, me.calendars[id]);
+        rcmail.http_post('calendar', { action:'subscribe', c:{ id:id, active:me.calendars[id].active?1:0 } });
+
+        e.stopPropagation();
+      }
+    });
+
+    // register dbl-click handler to open calendar edit dialog
+    $(rcmail.gui_objects.calendarslist).on('dblclick', ':not(.virtual) > .calname', function(e){
+      var id = $(this).closest('li').attr('id').replace(/^rcmlical/, '');
+      me.calendar_edit_dialog(me.calendars[id]);
+    });
+
     // select default calendar
     if (settings.default_calendar && this.calendars[settings.default_calendar] && !this.calendars[settings.default_calendar].readonly)
       this.selected_calendar = settings.default_calendar;
diff --git a/plugins/calendar/drivers/kolab/kolab_driver.php b/plugins/calendar/drivers/kolab/kolab_driver.php
index 28eb8ba5..974a3d3d 100644
--- a/plugins/calendar/drivers/kolab/kolab_driver.php
+++ b/plugins/calendar/drivers/kolab/kolab_driver.php
@@ -88,16 +88,16 @@ class kolab_driver extends calendar_driver
     return $this->calendars;
   }
 
-
   /**
    * Get a list of available calendars from this source
    *
    * @param bool $active   Return only active calendars
    * @param bool $personal Return only personal calendars
+   * @param object $tree   Reference to hierarchical folder tree object
    *
    * @return array List of calendars
    */
-  public function list_calendars($active = false, $personal = false)
+  public function list_calendars($active = false, $personal = false, &$tree = null)
   {
     // attempt to create a default calendar for this user
     if (!$this->has_writeable) {
@@ -112,7 +112,7 @@ class kolab_driver extends calendar_driver
 
     // include virtual folders for a full folder tree
     if (!$active && !$personal && !$this->rc->output->ajax_call && in_array($this->rc->action, array('index','')))
-      $folders = kolab_storage::folder_hierarchy($folders);
+      $folders = kolab_storage::folder_hierarchy($folders, $tree);
 
     foreach ($folders as $id => $cal) {
       $fullname = $cal->get_name();
@@ -124,6 +124,7 @@ class kolab_driver extends calendar_driver
           'id' => $cal->id,
           'name' => $fullname,
           'listname' => $listname,
+          'editname' => $cal->get_foldername(),
           'virtual' => true,
           'readonly' => true,
         );
@@ -1106,6 +1107,11 @@ class kolab_driver extends calendar_driver
    */
   public function calendar_form($action, $calendar, $formfields)
   {
+    // show default dialog for birthday calendar
+    if ($calendar['id'] == self::BIRTHDAY_CALENDAR_ID) {
+      return parent::calendar_form($action, $calendar, $formfields);
+    }
+
     if ($calendar['id'] && ($cal = $this->calendars[$calendar['id']])) {
       $folder = $cal->get_realname(); // UTF7
       $color  = $cal->get_color();
diff --git a/plugins/calendar/lib/calendar_ui.php b/plugins/calendar/lib/calendar_ui.php
index 984ce03b..117b9242 100644
--- a/plugins/calendar/lib/calendar_ui.php
+++ b/plugins/calendar/lib/calendar_ui.php
@@ -187,45 +187,108 @@ class calendar_ui
    */
   function calendar_list($attrib = array())
   {
-    $calendars = $this->cal->driver->list_calendars();
+    $html = '';
+    $jsenv = array();
+    $calendars = $this->cal->driver->list_calendars(false, false, $tree);
+
+    // walk folder tree
+    if (is_object($tree)) {
+      $html = $this->list_tree_html($tree, $calendars, $jsenv, $attrib);
+
+      // append birthdays calendar which isn't part of $tree
+      if ($bdaycal = $calendars[calendar_driver::BIRTHDAY_CALENDAR_ID]) {
+        $calendars = array(calendar_driver::BIRTHDAY_CALENDAR_ID => $bdaycal);
+      }
+      else {
+        $calendars = array();  // clear array for flat listing
+      }
+    }
+    else {
+      // fall-back to flat folder listing
+      $attrib['class'] .= ' flat';
+    }
 
-    $li = '';
     foreach ((array)$calendars as $id => $prop) {
       if ($attrib['activeonly'] && !$prop['active'])
         continue;
-      
-      unset($prop['user_id']);
-      $prop['alarms'] = $this->cal->driver->alarms;
-      $prop['attendees'] = $this->cal->driver->attendees;
-      $prop['freebusy'] = $this->cal->driver->freebusy;
-      $prop['attachments'] = $this->cal->driver->attachments;
-      $prop['undelete'] = $this->cal->driver->undelete;
-      $prop['feedurl'] = $this->cal->get_url(array('_cal' => $this->cal->ical_feed_hash($id) . '.ics', 'action' => 'feed'));
 
-      if (!$prop['virtual'])
-        $jsenv[$id] = $prop;
-
-      $html_id = html_identifier($id);
-      $class = 'cal-'  . asciiwords($id, true);
-      $title = $prop['name'] != $prop['listname'] ? html_entity_decode($prop['name'], ENT_COMPAT, RCMAIL_CHARSET) : '';
-
-      if ($prop['virtual'])
-        $class .= ' virtual';
-      else if ($prop['readonly'])
-        $class .= ' readonly';
-      if ($prop['class_name'])
-        $class .= ' '.$prop['class_name'];
-
-      $li .= html::tag('li', array('id' => 'rcmlical' . $html_id, 'class' => $class),
-        ($prop['virtual'] ? '' : html::tag('input', array('type' => 'checkbox', 'name' => '_cal[]', 'value' => $id, 'checked' => $prop['active']), '') .
-        html::span('handle', ' ')) .
-        html::span(array('class' => 'calname', 'title' => $title), $prop['listname']));
+      $html .= html::tag('li', array('id' => 'rcmlical' . rcube_utils::html_identifier($id)),
+        $content = $this->calendar_list_item($id, $prop, $jsenv)
+      );
     }
 
     $this->rc->output->set_env('calendars', $jsenv);
     $this->rc->output->add_gui_object('calendarslist', $attrib['id']);
 
-    return html::tag('ul', $attrib, $li, html::$common_attrib);
+    return html::tag('ul', $attrib, $html, html::$common_attrib);
+  }
+  
+  /**
+   * Return html for a structured list <ul> for the mailbox tree
+   */
+  public function list_tree_html(&$node, &$data, &$jsenv, $attrib)
+  {
+    $out = '';
+    foreach ($node->children as $folder) {
+      $id = $folder->id;
+      $prop = $data[$id];
+
+      $content = $this->calendar_list_item($id, $prop, $jsenv);
+
+      if (!empty($folder->children)) {
+        $content .= html::tag('ul', array('style' => ($is_collapsed ? "display:none;" : null)),
+          $this->list_tree_html($folder, $data, $jsenv, $attrib));
+      }
+
+      if (strlen($content)) {
+        $out .= html::tag('li', array(
+            'id' => 'rcmlical' . rcube_utils::html_identifier($id),
+            'class' => $prop['virtual'] ? 'virtual' : '',
+          ),
+          $content);
+      }
+    }
+
+    return $out;
+  }
+
+  /**
+   * Helper method to build a calendar list item (HTML content and js data)
+   */
+  protected function calendar_list_item($id, $prop, &$jsenv)
+  {
+    unset($prop['user_id']);
+    $prop['alarms']      = $this->cal->driver->alarms;
+    $prop['attendees']   = $this->cal->driver->attendees;
+    $prop['freebusy']    = $this->cal->driver->freebusy;
+    $prop['attachments'] = $this->cal->driver->attachments;
+    $prop['undelete']    = $this->cal->driver->undelete;
+    $prop['feedurl']     = $this->cal->get_url(array('_cal' => $this->cal->ical_feed_hash($id) . '.ics', 'action' => 'feed'));
+
+    if (!$prop['virtual'])
+      $jsenv[$id] = $prop;
+
+    $class = 'calendar cal-'  . asciiwords($id, true);
+    $title = $prop['name'] != $prop['listname'] ? html_entity_decode($prop['name'], ENT_COMPAT, RCMAIL_CHARSET) : '';
+    $is_collapsed = false; // TODO: determine this somehow?
+
+    if ($prop['virtual'])
+      $class = 'folder virtual';
+    else if ($prop['readonly'])
+      $class .= ' readonly';
+    if ($prop['class_name'])
+      $class .= ' '.$prop['class_name'];
+
+    $content = '';
+    if (!$attrib['activeonly'] || $prop['active']) {
+      $content = html::div($class,
+        ($prop['virtual'] ? '' : html::tag('input', array('type' => 'checkbox', 'name' => '_cal[]', 'value' => $id, 'checked' => $prop['active']), '') .
+        html::span('handle', ' ')) .
+        html::span(array('class' => 'calname', 'title' => $title), $prop['editname'] ? Q($prop['editname']) : $prop['listname'])
+      );
+    }
+
+    return $content;
   }
 
   /**
diff --git a/plugins/calendar/skins/larry/calendar.css b/plugins/calendar/skins/larry/calendar.css
index f47032fe..1ffaea8b 100644
--- a/plugins/calendar/skins/larry/calendar.css
+++ b/plugins/calendar/skins/larry/calendar.css
@@ -164,45 +164,64 @@ pre {
 	right: 0;
 }
 
-#calendarslist li {
-	margin: 0;
-	height: 20px;
-	padding: 6px 8px 2px;
-	display: block;
-	position: relative;
+#calendars .scroller {
+	top: 68px;
 }
 
-#calendarslist li.virtual {
-	height: 12px;
+#calendarslist li {
+	margin: 0;
+	position: relative;
 }
 
 #calendarslist li label {
 	display: block;
 }
 
+#calendarslist li div.folder,
+#calendarslist li div.calendar {
+	position: relative;
+	height: 28px;
+}
+
+#calendarslist li div.virtual {
+	height: 22px;
+}
+
+
 #calendarslist li span.calname {
 	display: block;
+	padding: 0px 30px 2px 2px;
 	position: absolute;
-	top: 6px;
-	left: 26px;
-	right: 24px;
+	top: 7px;
+	left: 38px;
+	right: 22px;
 	cursor: default;
 	background: url(images/calendars.png) right 20px no-repeat;
-	padding-bottom: 2px;
-	padding-right: 30px;
 	overflow: hidden;
 	text-overflow: ellipsis;
 	white-space: nowrap;
 	color: #004458;
 }
 
+#calendarslist li div.virtual > span.calname {
+	color: #aaa;
+	top: 4px;
+	left: 20px;
+}
+
+#calendarslist.flat li span.calname {
+	left: 24px;
+}
+
 #calendarslist li span.handle {
 	display: inline-block;
+	position: absolute;
+	top: 8px;
+	right: 6px;
 	padding: 0;
-	border-radius: 7px;
-	margin-right: 6px;
 	width: 10px;
 	height: 10px;
+	border-radius: 7px;
 	font-size: 0.8em;
 	border: 1px solid rgba(0, 0, 0, 0.5);
 	-webkit-box-shadow: inset 0px 0 1px 1px rgba(0, 0, 0, 0.3);
@@ -212,43 +231,65 @@ pre {
 
 #calendarslist li input {
 	position: absolute;
-	top: 4px;
-	right: 5px;
+	top: 5px;
+	left: 18px;
+}
+
+#calendarslist li div.treetoggle {
+	top: 8px;
+}
+
+#calendarslist li.virtual div.treetoggle {
+	top: 6px;
+}
+
+#calendarslist.flat li input {
+	left: 4px;
+}
+
+#calendarslist ul li div.folder,
+#calendarslist ul li div.calendar {
+	margin-left: 16px;
+}
+
+#calendarslist ul ul li div.folder,
+#calendarslist ul ul li div.calendar {
+	margin-left: 32px;
+}
+
+#calendarslist ul ul ul li div.folder,
+#calendarslist ul ul ul li div.calendar {
+	margin-left: 48px;
 }
 
 #calendarslist li.selected {
 	background-color: #c7e3ef;
 }
 
-#calendarslist li.selected span.calname {
+#calendarslist li.selected > span.calname {
 	font-weight: bold;
 }
 
-#calendarslist li.readonly span.calname {
+#calendarslist div.readonly span.calname {
 	background-position: right -20px;
 }
 
-#calendarslist li.other span.calname {
+#calendarslist div.other span.calname {
 	background-position: right -38px;
 }
 
-#calendarslist li.other.readonly span.calname {
+#calendarslist div.other.readonly span.calname {
 	background-position: right -56px;
 }
 
-#calendarslist li.shared span.calname {
+#calendarslist div.shared span.calname {
 	background-position: right -74px;
 }
 
-#calendarslist li.shared.readonly span.calname {
+#calendarslist div.shared.readonly span.calname {
 	background-position: right -92px;
 }
 
-#calendarslist li.virtual span.calname {
-	color: #aaa;
-	top: 2px;
-}
-
 #calfeedurl,
 #caldavurl {
 	width: 98%;
diff --git a/plugins/calendar/skins/larry/templates/calendar.html b/plugins/calendar/skins/larry/templates/calendar.html
index debe7ec4..0842cf03 100644
--- a/plugins/calendar/skins/larry/templates/calendar.html
+++ b/plugins/calendar/skins/larry/templates/calendar.html
@@ -23,8 +23,15 @@
 
 		<div id="calendars" class="uibox listbox" style="visibility:hidden">
 			<h2 class="boxtitle"><roundcube:label name="calendar.calendars" /></h2>
+			<div class="listsearchbox">
+				<div class="searchbox">
+					<input type="text" name="q" id="calendarlistsearch" />
+					<a class="iconbutton searchicon"></a>
+					<roundcube:button command="reset-listsearch" id="calendarlistsearch-reset" class="iconbutton reset" title="resetsearch" content="x" />
+				</div>
+			</div>
 			<div class="scroller withfooter">
-			<roundcube:object name="plugin.calendar_list" id="calendarslist" class="listing" />
+			<roundcube:object name="plugin.calendar_list" id="calendarslist" class="treelist listing" />
 			</div>
 			<div class="boxfooter">
 				<roundcube:button command="calendar-create" type="link" title="calendar.createcalendar" class="listbutton add disabled" classAct="listbutton add" innerClass="inner" content="+" /><roundcube:button name="calendaroptionslink" id="calendaroptionsmenulink" type="link" title="moreactions" class="listbutton groupactions" onclick="UI.show_popup('calendaroptionsmenu', undefined, { above:true });return false" innerClass="inner" content="&#9881;" />
diff --git a/plugins/libkolab/lib/kolab_storage.php b/plugins/libkolab/lib/kolab_storage.php
index 52df0165..9504e8fa 100644
--- a/plugins/libkolab/lib/kolab_storage.php
+++ b/plugins/libkolab/lib/kolab_storage.php
@@ -756,43 +756,54 @@ class kolab_storage
      * Check the folder tree and add the missing parents as virtual folders
      *
      * @param array $folders Folders list
+     * @param object $tree   Reference to the root node of the folder tree
      *
-     * @return array Folders list
+     * @return array Flat folders list
      */
-    public static function folder_hierarchy($folders)
+    public static function folder_hierarchy($folders, &$tree)
     {
         $_folders = array();
-        $existing = array_map(function($folder){ return $folder->get_name(); }, $folders);
         $delim    = rcube::get_instance()->get_storage()->get_hierarchy_delimiter();
+        $tree     = new virtual_kolab_storage_folder('', '<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)) {
+            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($path) > 1 && ($parent = join($delim, $path))) {
-                    $name = kolab_storage::object_name($parent, $folder->get_namespace());
-                    if (!in_array($name, $existing)) {
-                        $parents[$parent] = new virtual_kolab_storage_folder($parent, $name, $folder->get_namespace());
-                        $existing[] = $name;
-                    }
-
+                while (count($path) >= $depth && ($parent = join($delim, $path))) {
                     array_pop($path);
+                    $name = kolab_storage::object_name($parent, $folder->get_namespace());
+                    if (!$refs[$parent]) {
+                        $refs[$parent] = new virtual_kolab_storage_folder($parent, $name, $folder->get_namespace(), join($delim, $path));
+                        $parents[] = $refs[$parent];
+                    }
                 }
 
                 if (!empty($parents)) {
-                    $parents = array_reverse(array_values($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]);
         }
@@ -1164,13 +1175,18 @@ class virtual_kolab_storage_folder
     public $id;
     public $name;
     public $namespace;
+    public $parent = '';
+    public $children = array();
     public $virtual = true;
+    protected $displayname;
 
-    public function __construct($realname, $name, $ns)
+    public function __construct($name, $dispname, $ns, $parent = '')
     {
-        $this->id        = kolab_storage::folder_id($realname);
+        $this->id        = kolab_storage::folder_id($name);
         $this->name      = $name;
         $this->namespace = $ns;
+        $this->parent    = $parent;
+        $this->displayname = $dispname;
     }
 
     public function get_namespace()
@@ -1181,6 +1197,12 @@ class virtual_kolab_storage_folder
     public function get_name()
     {
         // this is already kolab_storage::object_name() result
-        return $this->name;
+        return $this->displayname;
+    }
+
+    public function get_foldername()
+    {
+        $parts = explode('/', $this->name);
+        return rcube_charset::convert(end($parts), 'UTF7-IMAP');
     }
 }
diff --git a/plugins/libkolab/lib/kolab_storage_folder.php b/plugins/libkolab/lib/kolab_storage_folder.php
index d625cc5e..7db493d2 100644
--- a/plugins/libkolab/lib/kolab_storage_folder.php
+++ b/plugins/libkolab/lib/kolab_storage_folder.php
@@ -47,6 +47,12 @@ class kolab_storage_folder
      * @var object
      */
     public $cache;
+    
+    /**
+     * List of direct child folders
+     * @var array
+     */
+    public $children = array();
 
     private $type_annotation;
     private $namespace;
@@ -217,6 +223,18 @@ class kolab_storage_folder
     }
 
 
+    /**
+     * Getter for the top-end folder name (not the entire path)
+     *
+     * @return string Name of this folder
+     */
+    public function get_foldername()
+    {
+        $parts = explode('/', $this->name);
+        return rcube_charset::convert(end($parts), 'UTF7-IMAP');
+    }
+
+
     /**
      * Get the color value stored in metadata
      *