Stop a event from bubbling in GWT

Question

I have the following snippet of code, changeTextArea is a TextArea object.

changeTextArea.addKeyboardListener(new KeyboardListenerAdapter()
  public void onKeyPress( Widget sender, char keyCode, int modifier){
    //do something
    //I WISH TO STOP THE EVENT THAT MAPS TO THIS KEYPRESS FROM BUBBLING ANY FURTHER
  }
}

How would I stop the Event that is causing this method to be called from bubbling up from changeTextArea into the Panels/Widgets/Composites/Whatever that contain changeTextArea. Put succinctly, how do I stop it from bubbling any further. Any help would be appreciated (especially code samples).

Answer 1

As far as I know you can't do it via a keyboard listener, but it is possible by adding an event preview using the DOM class:

DOM.addEventPreview(EventPreview preview)

Then when you get the event:

onEventPreview(Event event)

You should return false, to say you want to cancel the event. The Event object also supports this method:

public final void cancelBubble(boolean cancel)

Cancels bubbling for the given event. This will stop the event from being propagated to parent elements.

You can find more details here: http://google-web-toolkit.googlecode.com/svn/javadoc/1.5/index.html?overview-summary.html

Answer 2

You can definitely use the Event's cancelBubble() and preventDefault() methods from within any code that has access to the Event. There's no need to have an event preview...