private function forceAutoStackOnDone(Cardwall_OnTop_Config_ColumnCollection $columns, Cardwall_UserPreferences_UserPreferencesAutostack $autostack_preferences)
 {
     foreach ($columns as $column) {
         if (strcasecmp($column->label, 'done') == 0) {
             $autostack_preferences->forceColumnAutoStacked($column);
         }
     }
 }