code: protected void doSetController(Element element, GraphicsController controller, int eventMask) {
  		if (element != null) {
  			Dom.setEventListener(element, new EventListenerHelper(element, controller, eventMask));
  			Dom.sinkEvents(element, eventMask);
  		}
  	}
docs: Set the controller on an element of this <code>GraphicsContext</code> so it can react to events.
  
  @param element
  the element on which the controller should be set
  @param controller
  The new <code>GraphicsController</code>
  @param eventMask
  a bitmask to specify which events to listen for {@link com.google.gwt.user.client.Event}