public function addNotification($notification)
    {
        $this->_mixer->getRepository()
        ->registerCallback('before.update', array($this, 'resetStats'), array($this->_mixer));

        $this->_mixer->getRepository()
        ->registerCallback('before.update', array($this, 'removeOldNotifications'), array($this->_mixer));

        $ids = clone $this->notificationIds;
        $ids[] = $notification->id;
        $this->set('notificationIds', $ids);

        $ids = clone $this->newNotificationIds;
        $ids[] = $notification->id;
        $this->set('newNotificationIds', $ids);
    }