code: public static PushButton newPushButton (Image defaultImage, Image overImage,
                                              Image downImage, ClickHandler onClick)
      {
          PushButton button = new PushButton(defaultImage, downImage);
          maybeAddClickHandler(button, onClick);
          button.getUpHoveringFace().setImage(overImage);
          return button;
      }
docs: Creates a PushButton with default(up), mouseover and mousedown states.