code: public static boolean isRealVisible(Widget widget) {
          if (widget == null || !widget.isAttached()) return false;
          Element elt = widget.getElement();
          return UIObject.isVisible(elt) && Mobile.isVisible(elt);
      }
docs: Expensive, based on jQuery, but gives realistic visibility (CSS rules, parent chain considered,
  width and height are explicitly set to 0, ...)
  <br> If you need logical visibility of this particular widget,
  use {@link UIObject#isVisible(Element elem)}