public class WindowProcessor {
	@Inject
	@Named("com.example.window")
	private MWindow window;

	@Execute
	public void execute() {
		System.out.println("Window: " + window);

		final IEclipseContext context = window.getContext();
		System.out.println("Context: " + context);
	}
}

<extension
      id="id1"
      point="org.eclipse.e4.workbench.model">
   <processor
         beforefragment="false"
         class="com.example.handlers.WindowProcessor">
      <element
            id="com.example.window">
      </element>
   </processor>
</extension>

public class YourProcessor {

	@Inject
	private IEventBroker eventBroker;
	
	private EventHandler addHandler = new EventHandler() {
		
		@Override
		public void handleEvent(Event event) {
			if (!(event.getProperty(UIEvents.EventTags.ELEMENT) instanceof MWindow))
				return;
			
			if (!UIEvents.isCREATE(event)) 
				return;
			
			// do something
		}
	};
	
	@Execute
	protected void init() {
		eventBroker.subscribe(UIEvents.Window.TOPIC_ALL, addHandler);
		//eventBroker.subscribe(UIEvents.TrimmedWindow.TOPIC_ALL, addHandler);
	}
	
}

package com.test.application.addons;

import javax.inject.Inject;
import javax.inject.Named;

import org.eclipse.e4.core.contexts.IEclipseContext;
import org.eclipse.e4.core.contexts.RunAndTrack;
import org.eclipse.e4.core.di.annotations.Execute;
import org.eclipse.e4.core.services.events.IEventBroker;
import org.eclipse.e4.ui.model.application.ui.basic.MWindow;
import org.eclipse.e4.ui.workbench.UIEvents;
import org.eclipse.e4.ui.workbench.modeling.IWindowCloseHandler;
import org.osgi.service.event.Event;
import org.osgi.service.event.EventHandler;

@SuppressWarnings("restriction")
public class QuitProcessor {
  
  private final MWindow window;
  private final IEventBroker eventBroker;
  
  @Inject
  public QuitProcessor(@Named("at.renbrand.sentinel.mainWindow")MWindow window, IEventBroker eventBroker){
    this.window = window;
    this.eventBroker = eventBroker;
  }
  
  @Execute
  void installIntoContext(){
    eventBroker.subscribe(UIEvents.Context.TOPIC_CONTEXT, new EventHandler(){

      @Override
      public void handleEvent(Event event) {
        if( UIEvents.isSET(event) ){
          if( window.equals( event.getProperty("ChangedElement") ) && window.getContext() != null ){
            // use RunAndTrack to get notified after the IWindowCloseHanlder was changed in the IEclipseContext
            window.getContext().runAndTrack(new RunAndTrack(){
              
              private final IWindowCloseHandler quitHandler = new QuitHandler();

              @Override
              public boolean changed(IEclipseContext context) {
                Object value = context.get(IWindowCloseHandler.class);  // access the context value to be reevaluated on every future change of the value
                
                if(!quitHandler.equals(value)){  // prevents endless loop
                  context.set(IWindowCloseHandler.class, quitHandler);
                }
                
                return true;  // ture keeps tracking and the quitHandler as the only opportunity
              }
              
            });
          }
        }
      }
      
    });
  }
}

 <extension
         id="id2"
         point="org.eclipse.e4.workbench.model">
      <processor
            beforefragment="false"
            class="com.test.application.addons.QuitProcessor">
         <element
               id="at.renbrand.sentinel.mainWindow">
         </element>
      </processor>
   </extension>