code: @Override
      public boolean addChild(Widget child, int index, boolean preventLayout) {
          return super.addChild(child, index, preventLayout);
      }
docs: Add another {@link Widget} as a child of this one.
  
  @param child
  The {@code Widget} to add as a child.
  @param index
  Position at which to add the child.
  @param preventLayout
  The {@code Widget} whether to call layout().
  @return {@code True} if {@code child} was added; {@code false} if
  {@code child} was previously added to this instance.