public function renderHTML(MvcEvent $event)
 {
     if (!$this->hasRunned) {
         $nEvent = new NotificationEvent();
         $nEvent->setNotifications($this->notifications);
         $this->trigger(NotificationEvent::EVENT_NOTIFICATION_HTML, $nEvent);
         $this->notifications = array();
         $this->hasRunned = true;
     }
     return $this;
 }