code: private synchronized void doOnAttached(final Widget parent) {
          if (parent != mParent) {
              mParent = parent;
              create();
              registerPickable();
              onAttached();
          }
      }
docs: Does post-{@linkplain GroupWidget#addChild(Widget) attachment} setup:
  <ul>
  <li>Runs GL thread {@linkplain #create() initialization}</li>
  <li>Registers for touch and focus notifications, if they are enabled</li>
  <li>Invokes {@link #onAttached()}
  </ul>
  
  @param parent
  The {@link GroupWidget} this instance is being
  {@linkplain GroupWidget#addChild(Widget) attached} to.