Flag virtual folders as read-only

plugins/calendar/drivers/kolab/kolab_driver.php

@@ -122,6 +122,7 @@ class kolab_driver extends calendar_driver
           'id' => $cal->id,
           'name' => $name,
           'virtual' => true,
+          'readonly' => true,
         );
       }
       else {

plugins/tasklist/drivers/kolab/tasklist_kolab_driver.php

@@ -104,6 +104,7 @@ class tasklist_kolab_driver extends tasklist_driver
                     'id' => $list_id,
                     'name' => $name,
                     'virtual' => true,
+                    'editable' => false,
                 );
                 continue;
             }