private EventHandler testHandler;
       @PostConstruct
       public void pc(IEventBroker eventBroker)
       {
               testHandler = new EventHandler() {
                       
                       @Override
                       public void handleEvent(Event event) {
                               Object part = event.getProperty(UIEvents.EventTags.ELEMENT);
                               boolean tbr =(Boolean) event.getProperty(UIEvents.EventTags.NEW_VALUE);
                               
                               System.out.println(event.getTopic().toString());
                               if (part instanceof MPart){
                                       System.out.println("Part "+((MPart)part).getElementId()+" is "+(!tbr?"NOT":"")+" visible");
                                       if(MessageDialog.openConfirm(Display.getCurrent().getActiveShell(), "Confirmation", "Do you really want to close? ")){
                                               System.out.println("exit!");
                                       }
                                       else{
                                       }
                               }
                       }
               };
               eventBroker.subscribe(UIEvents.UIElement.TOPIC_TOBERENDERED, testHandler);
       }