code: public void setSize(int width, int height) {
      rootElement.getStyle().setWidth(width, Unit.PX);
      rootElement.getStyle().setHeight(height, Unit.PX);
    }
docs: Sizes or resizes the root element that contains the PlayN view.
  @param width the new width, in pixels, of the view.
  @param height the new height, in pixels, of the view.