/**
  * Get attachment body
  * @see calendar_driver::get_attachment_body()
  */
 public function get_attachment_body($id, $event)
 {
     // find the actual folder this event resides in
     if (!empty($event['_folder_id'])) {
         $cal = $this->cal->driver->get_calendar($event['_folder_id']);
     } else {
         $cal = null;
         foreach (kolab_storage::list_folders('', '*', 'event', null) as $foldername) {
             $cal = new kolab_calendar($foldername, $this->cal);
             if ($cal->ready && $cal->storage && $cal->get_event($event['id'])) {
                 break;
             }
         }
     }
     if ($cal && $cal->storage) {
         return $cal->get_attachment_body($id, $event);
     }
     return false;
 }