code: private boolean isCaptionEvent(NativeEvent event) {
  
          EventTarget target = event.getEventTarget();
          if (com.google.gwt.dom.client.Element.is(target)) {
              return m_caption.getElement().isOrHasChild(com.google.gwt.dom.client.Element.as(target));
          }
          return false;
      }
docs: Checks if the target of the given event is the caption or a child of the caption.<p>
  
  @param event the event to check
  
  @return <code>true</code> if the target of the given event is the caption <code>false</code> otherwise