@Override
 public void onResize() {
   super.onResize();
   if (isAttached()) {
     ResizeEvent.fire(this, getElement().getOffsetWidth(), getElement().getOffsetHeight());
   }
 }
 @Override
 public void add(Widget widget) {
   widget.getElement().getStyle().clearWidth();
   widget.getElement().getStyle().clearHeight();
   super.add(widget);
   AddEvent.fire(this, widget);
 }
 @Override
 public void setVisible(boolean visible) {
   boolean oldValue = isVisible();
   super.setVisible(visible);
   if (oldValue != visible) {
     if (visible) {
       ShowEvent.fire(this, this);
     } else {
       HideEvent.fire(this, this);
     }
   }
 }
 public void setDividerLocation(int aValue) {
   if (dividerLocation != aValue) {
     dividerLocation = aValue;
     if (firstWidget != null) super.setWidgetSize(firstWidget, aValue);
   }
 }