/** Deactivate the listeners. */
 private void deleteLayersModelRootNotifier() {
   /**
    * Listen on layersModel to be inform when the application object is created. When it is
    * created, we can listen on it.
    */
   if (layersModelEventRootNotifier != null) {
     layersModelEventRootNotifier.removeEventListener(
         layersStackApplicationLifeCycleEventListener);
     layersModelEventRootNotifier.dispose();
     layersModelEventRootNotifier = null;
   }
 }
 /** Activate the listeners. */
 private void createLayersModelRootNotifier() {
   /**
    * Listen on layersModel to be inform when the application object is created. When it is
    * created, we can listen on it.
    */
   layersModelEventRootNotifier = new LayersModelEventRootNotifier(layersModel);
   layersModelEventRootNotifier.addEventListener(layersStackApplicationLifeCycleEventListener);
 }
  /**
   * Remove the specified listener from the list of listeners.
   *
   * @param listener
   */
  public void removeLayersStackApplicationLifeCycleEventListener(
      ILayersModelRootEventListener listener) {

    layersModelEventRootNotifier.removeEventListener(listener);
  }
 /**
  * Add the specified listener to the list of listener. Do not add it if the listener is already in
  * the list.
  *
  * @param listener
  */
 public void addLayersStackApplicationLifeCycleEventListener(
     ILayersModelRootEventListener listener) {
   // Add to the inner notifier
   layersModelEventRootNotifier.addEventListener(listener);
 }