/** 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);
 }
 /**
  * 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);
 }