diff --git a/plugins/calendar/calendar.php b/plugins/calendar/calendar.php
index 43818247..1f008023 100644
--- a/plugins/calendar/calendar.php
+++ b/plugins/calendar/calendar.php
@@ -1957,7 +1957,8 @@ class calendar extends rcube_plugin
    */
   public function attachment_upload()
   {
-    $this->lib->attachment_upload(self::SESSION_KEY, 'cal-');
+    $handler = new kolab_attachments_handler();
+    $handler->attachment_upload(self::SESSION_KEY, 'cal-');
   }
 
   /**
@@ -1965,9 +1966,11 @@ class calendar extends rcube_plugin
    */
   public function attachment_get()
   {
+    $handler = new kolab_attachments_handler();
+
     // show loading page
     if (!empty($_GET['_preload'])) {
-        return $this->lib->attachment_loading_page();
+        return $handler->attachment_loading_page();
     }
 
     $event_id = rcube_utils::get_input_value('_event', rcube_utils::INPUT_GPC);
@@ -1992,12 +1995,7 @@ class calendar extends rcube_plugin
 
     // show part page
     if (!empty($_GET['_frame'])) {
-        $this->lib->attachment = $attachment;
-        $this->register_handler('plugin.attachmentframe', array($this->lib, 'attachment_frame'));
-        $this->register_handler('plugin.attachmentcontrols', array($this->lib, 'attachment_header'));
-        $this->rc->output->set_env('filename', $attachment['name']);
-        $this->rc->output->set_env('mimetype', $attachment['mimetype']);
-        $this->rc->output->send('calendar.attachment');
+        $handler->attachment_page($attachment);
     }
     // deliver attachment content
     else if ($attachment) {
@@ -2005,7 +2003,7 @@ class calendar extends rcube_plugin
             $attachment['body'] = $this->driver->get_attachment_body($id, $event);
         }
 
-        $this->lib->attachment_get($attachment);
+        $handler->attachment_get($attachment);
     }
 
     // if we arrive here, the requested part was not found
diff --git a/plugins/calendar/calendar_ui.js b/plugins/calendar/calendar_ui.js
index 775f9350..966dc448 100644
--- a/plugins/calendar/calendar_ui.js
+++ b/plugins/calendar/calendar_ui.js
@@ -284,86 +284,32 @@ function rcube_calendar_ui(settings)
         return date.getHours() >= settings['work_start'] && date.getHours() < settings['work_end'];
     };
 
-    var load_attachment = function(event, att)
+    var load_attachment = function(data)
     {
-      var query = { _id: att.id, _event: event.recurrence_id || event.id, _cal:event.calendar, _frame: 1 };
+      var event = data.record,
+        query = {_id: data.attachment.id, _event: event.recurrence_id || event.id, _cal: event.calendar};
+
       if (event.rev)
         query._rev = event.rev;
 
       if (event.calendar == "--invitation--itip")
         $.extend(query, {_uid: event._uid, _part: event._part, _mbox: event._mbox});
 
-      // open attachment in frame if it's of a supported mimetype
-      if (id && att.mimetype && $.inArray(att.mimetype, settings.mimetypes)>=0) {
-        if (rcmail.open_window(rcmail.url('get-attachment', query), true, true)) {
-          return;
-        }
-      }
-
-      query._frame = null;
-      query._download = 1;
-      rcmail.goto_url('get-attachment', query, false);
+      libkolab.load_attachment(query, data.attachment);
     };
 
     // build event attachments list
     var event_show_attachments = function(list, container, event, edit)
     {
-      var i, id, len, img, content, li, elem,
-        ul = document.createElement('UL');
-      ul.className = 'attachmentslist';
-
-      for (i=0, len=list.length; i<len; i++) {
-        elem = list[i];
-        li = document.createElement('LI');
-        li.className = elem.classname;
-
-        if (edit) {
-          rcmail.env.attachments[elem.id] = elem;
-          // delete icon
-          content = $('<a href="#delete" />')
-            .attr('title', rcmail.gettext('delete'))
-            .attr('aria-label', rcmail.gettext('delete') + ' ' + Q(elem.name))
-            .addClass('delete')
-            .click({id: elem.id}, function(e) { remove_attachment(this, e.data.id); return false; });
-
-          if (!rcmail.env.deleteicon)
-            content.html(rcmail.gettext('delete'));
-          else {
-            img = document.createElement('IMG');
-            img.src = rcmail.env.deleteicon;
-            img.alt = rcmail.gettext('delete');
-            content.append(img);
-          }
-
-          content.appendTo(li);
-        }
-
-        // name/link
-        content = $('<a href="#load" />')
-          .html(Q(elem.name))
-          .addClass('file')
-          .click({event: event, att: elem}, function(e) {
-            load_attachment(e.data.event, e.data.att);
-            return false;
-          })
-          .appendTo(li);
-
-        ul.appendChild(li);
-      }
-
-      if (edit && rcmail.gui_objects.attachmentlist) {
-        ul.id = rcmail.gui_objects.attachmentlist.id;
-        rcmail.gui_objects.attachmentlist = ul;
-      }
-
-      container.empty().append(ul);
+      libkolab.list_attachments(list, container, edit, event,
+        function(id) { remove_attachment(id); },
+        function(data) { load_attachment(data); }
+      );
     };
 
-    var remove_attachment = function(elem, id)
+    var remove_attachment = function(id)
     {
-      $(elem.parentNode).hide();
       rcmail.env.deleted_attachments.push(id);
-      delete rcmail.env.attachments[id];
     };
 
     // event details dialog (show only)
diff --git a/plugins/calendar/lib/calendar_ui.php b/plugins/calendar/lib/calendar_ui.php
index f99c658c..54e20a61 100644
--- a/plugins/calendar/lib/calendar_ui.php
+++ b/plugins/calendar/lib/calendar_ui.php
@@ -80,9 +80,6 @@ class calendar_ui
     $this->cal->register_handler('plugin.sensitivity_select', array($this, 'sensitivity_select'));
     $this->cal->register_handler('plugin.alarm_select', array($this, 'alarm_select'));
     $this->cal->register_handler('plugin.recurrence_form', array($this->cal->lib, 'recurrence_form'));
-    $this->cal->register_handler('plugin.attachments_form', array($this, 'attachments_form'));
-    $this->cal->register_handler('plugin.attachments_list', array($this, 'attachments_list'));
-    $this->cal->register_handler('plugin.filedroparea', array($this, 'file_drop_area'));
     $this->cal->register_handler('plugin.attendees_list', array($this, 'attendees_list'));
     $this->cal->register_handler('plugin.attendees_form', array($this, 'attendees_form'));
     $this->cal->register_handler('plugin.resources_form', array($this, 'resources_form'));
@@ -100,6 +97,8 @@ class calendar_ui
     $this->cal->register_handler('plugin.events_export_form', array($this, 'events_export_form'));
     $this->cal->register_handler('plugin.object_changelog_table', array('libkolab', 'object_changelog_table'));
     $this->cal->register_handler('plugin.searchform', array($this->rc->output, 'search_form'));  // use generic method from rcube_template
+
+    kolab_attachments_handler::ui();
   }
 
   /**
@@ -610,54 +609,6 @@ class calendar_ui
     );
   }
 
-  /**
-   * Generate the form for event attachments upload
-   */
-  function attachments_form($attrib = array())
-  {
-    // add ID if not given
-    if (!$attrib['id']) {
-      $attrib['id'] = 'rcmUploadForm';
-    }
-
-    return $this->rc->upload_form($attrib, 'uploadform', 'upload-file', array('multiple' => true));
-  }
-
-  /**
-   * Register UI object for HTML5 drag & drop file upload
-   */
-  function file_drop_area($attrib = array())
-  {
-      if ($attrib['id']) {
-          $this->rc->output->add_gui_object('filedrop', $attrib['id']);
-          $this->rc->output->set_env('filedrop', array('action' => 'upload', 'fieldname' => '_attachments'));
-      }
-  }
-
-  /**
-   * Generate HTML element for attachments list
-   */
-  function attachments_list($attrib = array())
-  {
-    if (!$attrib['id'])
-      $attrib['id'] = 'rcmAttachmentList';
-
-    $skin_path = $this->cal->local_skin_path();
-    if ($attrib['deleteicon']) {
-      $_SESSION[calendar::SESSION_KEY . '_deleteicon'] = $skin_path . $attrib['deleteicon'];
-      $this->rc->output->set_env('deleteicon', $skin_path . $attrib['deleteicon']);
-    }
-    if ($attrib['cancelicon'])
-      $this->rc->output->set_env('cancelicon', $skin_path . $attrib['cancelicon']);
-    if ($attrib['loadingicon'])
-      $this->rc->output->set_env('loadingicon', $skin_path . $attrib['loadingicon']);
-
-    $this->rc->output->add_gui_object('attachmentlist', $attrib['id']);
-    $this->attachmentlist_id = $attrib['id'];
-
-    return html::tag('ul', $attrib, '', html::$common_attrib);
-  }
-
   /**
    * Handler for calendar form template.
    * The form content could be overriden by the driver
diff --git a/plugins/libcalendaring/libcalendaring.php b/plugins/libcalendaring/libcalendaring.php
index 4ae37166..b2297e00 100644
--- a/plugins/libcalendaring/libcalendaring.php
+++ b/plugins/libcalendaring/libcalendaring.php
@@ -250,10 +250,6 @@ class libcalendaring extends rcube_plugin
         );
         $settings['today'] = $this->rc->gettext('today');
 
-        // define list of file types which can be displayed inline
-        // same as in program/steps/mail/show.inc
-        $settings['mimetypes'] = (array)$this->rc->config->get('client_mimetypes');
-
         return $settings;
     }
 
diff --git a/plugins/libkolab/lib/kolab_attachments_handler.php b/plugins/libkolab/lib/kolab_attachments_handler.php
index 821aaaf9..d38739e6 100644
--- a/plugins/libkolab/lib/kolab_attachments_handler.php
+++ b/plugins/libkolab/lib/kolab_attachments_handler.php
@@ -33,6 +33,61 @@ class kolab_attachments_handler
         $this->rc = rcmail::get_instance();
     }
 
+    public static function ui()
+    {
+        $rcmail = rcmail::get_instance();
+        $self   = new self;
+
+        $rcmail->output->add_handler('plugin.attachments_form', array($self, 'files_form'));
+        $rcmail->output->add_handler('plugin.attachments_list', array($self, 'files_list'));
+        $rcmail->output->add_handler('plugin.filedroparea', array($self, 'files_drop_area'));
+    }
+
+    /**
+     * Generate HTML element for attachments list
+     */
+    public function files_list($attrib = array())
+    {
+        if (!$attrib['id']) {
+            $attrib['id'] = 'kolabattachmentlist';
+        }
+
+        // define list of file types which can be displayed inline
+        // same as in program/steps/mail/show.inc
+        $this->rc->output->set_env('mimetypes', (array)$this->rc->config->get('client_mimetypes'));
+
+        $this->rc->output->add_gui_object('attachmentlist', $attrib['id']);
+
+        return html::tag('ul', $attrib, '', html::$common_attrib);
+    }
+
+    /**
+     * Generate the form for event attachments upload
+     */
+    public function files_form($attrib = array())
+    {
+        // add ID if not given
+        if (!$attrib['id']) {
+            $attrib['id'] = 'kolabuploadform';
+        }
+
+        return $this->rc->upload_form($attrib, 'uploadform', 'upload-file', array('multiple' => true));
+    }
+
+    /**
+     * Register UI object for HTML5 drag & drop file upload
+     */
+    public function files_drop_area($attrib = array())
+    {
+        // add ID if not given
+        if (!$attrib['id']) {
+            $attrib['id'] = 'kolabfiledroparea';
+        }
+
+        $this->rc->output->add_gui_object('filedrop', $attrib['id']);
+        $this->rc->output->set_env('filedrop', array('action' => 'upload', 'fieldname' => '_attachments'));
+    }
+
     /**
      * Displays attachment preview page
      */
@@ -40,6 +95,8 @@ class kolab_attachments_handler
     {
         $this->attachment = $attachment;
 
+        $this->rc->plugins->include_script('libkolab/libkolab.js');
+
         $this->rc->output->add_handler('plugin.attachmentframe', array($this, 'attachment_frame'));
         $this->rc->output->add_handler('plugin.attachmentcontrols', array($this, 'attachment_header'));
         $this->rc->output->set_env('filename', $attachment['name']);
diff --git a/plugins/libkolab/libkolab.js b/plugins/libkolab/libkolab.js
index 56c8dee7..1b669846 100644
--- a/plugins/libkolab/libkolab.js
+++ b/plugins/libkolab/libkolab.js
@@ -25,7 +25,7 @@
  * for the JavaScript code in this file.
  */
 
-var libkolab_audittrail = {}
+var libkolab_audittrail = {}, libkolab = {};
 
 libkolab_audittrail.quote_html = function(str)
 {
@@ -221,6 +221,73 @@ libkolab_audittrail.dialog_resize = function(id, height, width)
     $(id).dialog('option', { height: Math.min(h-20, height+130), width: Math.min(w-20, width+50) });
 };
 
+/**
+ * Open an attachment either in a browser window for inline view or download it
+ */
+libkolab.load_attachment = function(query, attachment)
+{
+    query._frame = 1;
+
+    // open attachment in frame if it's of a supported mimetype similar as in app.js
+    if (attachment.id && attachment.mimetype && $.inArray(attachment.mimetype, rcmail.env.mimetypes) >= 0) {
+        if (rcmail.open_window(rcmail.url('get-attachment', query), true, true)) {
+            return;
+        }
+    }
+
+    query._frame = null;
+    query._download = 1;
+    rcmail.goto_url('get-attachment', query, false);
+};
+
+/**
+ * Build attachments list element
+ */
+libkolab.list_attachments = function(list, container, edit, data, ondelete, onload)
+{
+    var ul = $('<ul>').addClass('attachmentslist');
+
+    $.each(list || [], function(i, elem) {
+        var li = $('<li>').addClass(elem.classname);
+
+        // name/link
+        $('<a>').attr({href: '#load', 'class': 'filename'})
+            .append($('<span class="attachment-name">').text(elem.name))
+            .click({record: data, attachment: elem}, function(e) {
+                if (onload) {
+                    onload(e.data);
+                }
+                return false;
+            })
+            .appendTo(li);
+
+        if (edit) {
+            rcmail.env.attachments[elem.id] = elem;
+            // delete link
+            $('<a>').attr({href: '#delete', title: rcmail.gettext('delete'), 'class': 'delete'})
+                .click({id: elem.id}, function(e) {
+                    $(this.parentNode).hide();
+                    delete rcmail.env.attachments[e.data.id];
+                    if (ondelete) {
+                        ondelete(e.data.id);
+                    }
+                    return false;
+                })
+                .appendTo(li);
+        }
+
+        ul.append(li);
+    });
+
+    if (edit && rcmail.gui_objects.attachmentlist) {
+        ul.id = rcmail.gui_objects.attachmentlist.id;
+        rcmail.gui_objects.attachmentlist = ul.get(0);
+    }
+
+    container.empty().append(ul);
+};
+
+
 function kolab_folderlist(node, p)
 {
     // extends treelist.js
@@ -533,26 +600,28 @@ function kolab_folderlist(node, p)
     });
 
     this.container.on('click', 'a.remove', function(e) {
-      var li = $(this).closest('li'),
-          id = li.attr('id').replace(new RegExp('^'+p.id_prefix), '');
+        var li = $(this).closest('li'),
+            id = li.attr('id').replace(new RegExp('^'+p.id_prefix), '');
 
-      if (me.is_search()) {
-          id = id.replace(/--xsR$/, '');
-          li = $(me.get_item(id, true));
-      }
+        if (me.is_search()) {
+            id = id.replace(/--xsR$/, '');
+            li = $(me.get_item(id, true));
+        }
 
-      if (p.id_decode)
-          id = p.id_decode(id);
+        if (p.id_decode)
+            id = p.id_decode(id);
 
-      me.triggerEvent('remove', { id: id, item: li });
+        me.triggerEvent('remove', { id: id, item: li });
 
-      e.stopPropagation();
-      return false;
+        e.stopPropagation();
+        return false;
     });
 }
 
 // link prototype from base class
-kolab_folderlist.prototype = rcube_treelist_widget.prototype;
+if (window.rcube_treelist_widget) {
+    kolab_folderlist.prototype = rcube_treelist_widget.prototype;
+}
 
 
 window.rcmail && rcmail.addEventListener('init', function(e) {
@@ -599,7 +668,7 @@ window.rcmail && rcmail.addEventListener('init', function(e) {
     }
 
     if (rcmail.env.action == 'get-attachment') {
-        if (rcmail.rcmail.gui_objects.attachmentframe) {
+        if (rcmail.gui_objects.attachmentframe) {
             rcmail.gui_objects.messagepartframe = rcmail.gui_objects.attachmentframe;
             rcmail.enable_command('image-scale', 'image-rotate', !!/^image\//.test(rcmail.env.mimetype));
             rcmail.register_command('print-attachment', function() {
diff --git a/plugins/tasklist/tasklist.js b/plugins/tasklist/tasklist.js
index 9060817f..cd2a917a 100644
--- a/plugins/tasklist/tasklist.js
+++ b/plugins/tasklist/tasklist.js
@@ -2611,89 +2611,39 @@ function rcube_tasklist_ui(settings)
     /**
      * Open a task attachment either in a browser window for inline view or download it
      */
-    function load_attachment(rec, att)
+    function load_attachment(data)
     {
+        var rec = data.record;
+
         // can't open temp attachments
         if (!rec.id || rec.id < 0)
             return false;
 
-        var query = { _id: att.id, _t: rec.recurrence_id||rec.id, _list:rec.list, _frame: 1 };
+        var query = {_id: data.attachment.id, _t: rec.recurrence_id || rec.id, _list: rec.list};
 
         if (rec.rev)
             query._rev = rec.rev;
 
-        // open attachment in frame if it's of a supported mimetype
-        // similar as in app.js and calendar_ui.js
-        if (att.id && att.mimetype && $.inArray(att.mimetype, settings.mimetypes)>=0) {
-            if (rcmail.open_window(rcmail.url('get-attachment', query), true, true)) {
-                return;
-            }
-        }
-
-        query._frame = null;
-        query._download = 1;
-        rcmail.goto_url('get-attachment', query, false);
+        libkolab.load_attachment(query, data.attachment);
     };
 
     /**
      * Build task attachments list
      */
-    function task_show_attachments(list, container, rec, edit)
+    function task_show_attachments(list, container, task, edit)
     {
-        var i, id, len, content, li, elem,
-            ul = $('<ul>').addClass('attachmentslist');
-
-        for (i=0, len=list.length; i<len; i++) {
-            elem = list[i];
-            li = $('<li>').addClass(elem.classname);
-
-            if (edit) {
-                rcmail.env.attachments[elem.id] = elem;
-                // delete icon
-                content = $('<a>').attr({href: '#delete', title: rcmail.gettext('delete'), 'class': 'delete'})
-                    .click({ id:elem.id }, function(e) {
-                        remove_attachment(this, e.data.id);
-                        return false;
-                    });
-
-                if (!rcmail.env.deleteicon) {
-                    // content.html(rcmail.gettext('delete'));
-                }
-                else {
-                    $('<img>').attr('src', rcmail.env.deleteicon).attr('alt', rcmail.gettext('delete')).appendTo(content);
-                }
-
-                li.append(content);
-            }
-
-            // name/link
-            $('<a>').attr({href: '#load', 'class': 'filename'})
-                .append($('<span class="attachment-name">').text(elem.name))
-                .click({ task:rec, att:elem }, function(e) {
-                    load_attachment(e.data.task, e.data.att);
-                    return false;
-                })
-                .appendTo(li);
-
-            ul.append(li);
-        }
-
-        if (edit && rcmail.gui_objects.attachmentlist) {
-            ul.id = rcmail.gui_objects.attachmentlist.id;
-            rcmail.gui_objects.attachmentlist = ul.get(0);
-        }
-
-        container.empty().append(ul);
+      libkolab.list_attachments(list, container, edit, task,
+        function(id) { remove_attachment(id); },
+        function(data) { load_attachment(data); }
+      );
     };
 
     /**
      *
      */
-    function remove_attachment(elem, id)
+    function remove_attachment(id)
     {
-        $(elem.parentNode).hide();
         me.selected_task.deleted_attachments.push(id);
-        delete rcmail.env.attachments[id];
     }
 
     /**
diff --git a/plugins/tasklist/tasklist_ui.php b/plugins/tasklist/tasklist_ui.php
index a8bfb170..0d762b24 100644
--- a/plugins/tasklist/tasklist_ui.php
+++ b/plugins/tasklist/tasklist_ui.php
@@ -146,9 +146,6 @@ class tasklist_ui
         $this->plugin->register_handler('plugin.tags_editline', array($this, 'tags_editline'));
         $this->plugin->register_handler('plugin.alarm_select', array($this, 'alarm_select'));
         $this->plugin->register_handler('plugin.recurrence_form', array($this->plugin->lib, 'recurrence_form'));
-        $this->plugin->register_handler('plugin.attachments_form', array($this, 'attachments_form'));
-        $this->plugin->register_handler('plugin.attachments_list', array($this, 'attachments_list'));
-        $this->plugin->register_handler('plugin.filedroparea', array($this, 'file_drop_area'));
         $this->plugin->register_handler('plugin.attendees_list', array($this, 'attendees_list'));
         $this->plugin->register_handler('plugin.attendees_form', array($this, 'attendees_form'));
         $this->plugin->register_handler('plugin.identity_select', array($this, 'identity_select'));
@@ -158,6 +155,8 @@ class tasklist_ui
         $this->plugin->register_handler('plugin.tasks_export_form', array($this, 'tasks_export_form'));
         $this->plugin->register_handler('plugin.tasks_import_form', array($this, 'tasks_import_form'));
 
+        kolab_attachments_handler::ui();
+
         $this->plugin->include_script('tasklist.js');
         $this->rc->output->include_script('treelist.js');
         $this->plugin->api->include_script('libkolab/libkolab.js');
@@ -412,44 +411,6 @@ class tasklist_ui
         return html::div($attrib, $input->show(''));
     }
 
-    /**
-     * Generate HTML element for attachments list
-     */
-    function attachments_list($attrib = array())
-    {
-        if (!$attrib['id']) {
-            $attrib['id'] = 'rcmtaskattachmentlist';
-        }
-
-        $this->register_gui_object('attachmentlist', $attrib['id']);
-
-        return html::tag('ul', $attrib, '', html::$common_attrib);
-    }
-
-    /**
-     * Generate the form for event attachments upload
-     */
-    function attachments_form($attrib = array())
-    {
-        // add ID if not given
-        if (!$attrib['id']) {
-            $attrib['id'] = 'rcmtaskuploadform';
-        }
-
-        return $this->rc->upload_form($attrib, 'uploadform', 'upload-file', array('multiple' => true));
-    }
-
-    /**
-     * Register UI object for HTML5 drag & drop file upload
-     */
-    function file_drop_area($attrib = array())
-    {
-        if ($attrib['id']) {
-            $this->register_gui_object('filedrop', $attrib['id']);
-            $this->rc->output->set_env('filedrop', array('action' => 'upload', 'fieldname' => '_attachments'));
-        }
-    }
-
     /**
      *
      */