/**
  * This is a hack...
  * @todo Do we need a WFObject::keyExists() function or similar that can "check" for a binding without having to call the accessor? or WFObject::canSetKey()? Or do binding need to have a "readyonly" or "writeonly" option?
  */
 function valueForUndefinedKey($key)
 {
     switch ($key) {
         case 'menuItemsMenuPath':
         case 'menuItemsNestedArray':
             return NULL;
             // we never return a value here, but we need to make it seem that we're a legitimate property so that bindings will work.
             break;
     }
     return parent::valueForUndefinedKey($key);
 }