code: public static MoveAnimation move (final PopupPanel target)
      {
          return new MoveAnimation(target) {
              @Override protected void updatePosition (int left, int top) {
                  target.setPopupPosition(left, top);
              }
              @Override protected void onStart () {
                  super.onStart();
                  if (!target.isShowing()) {
                      target.show();
                  }
                  target.setVisible(true);
              }
          };
      }
docs: Creates an animation that will move the specified popup panel. If the popup is not showing
  or not visible, it will be shown and made visible immediately after moving it to the start
  position. The returned animation is configured fluently, for example:
  
  <code>FX.move(target).from(x, y).to(dx, dy).onComplete(action).run(500);</code>