protected boolean addChild(Widget child, int index, boolean preventLayout) {
        return addChild(child, child.getSceneObject(), index, preventLayout);
    }
protected boolean addChild ( Widget child , int index , boolean preventLayout ) { return addChild ( child , child . getSceneObject ( ) , index , preventLayout ) ; }
Add another {@link Widget} as a child of this one. Overload to intercept all child adds.

@param child
The {@code Widget} to add as a child.
@param index
Position at which to add the child. Pass -1 to add at end.
@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.