[Bug] When using `PositionedBalloon`, Balloon can not process hitTest(gestures)

[note11g]

When using PositionedBalloon, Balloon can not process hitTest(gestures).

sample code:

bool isVisible = true;

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: ListView(
      children: [
        PositionedBalloon(
          show: isVisible,
          balloon: Balloon(
            child: Row(children: [
              Text("now go shopping, you got a event coin!"),
              IconButton(
                onPressed: () => setState(() => isVisible = false),
                icon: Icon(Icons.close)),
            ]),
            child: TextButton(
               onPressed: () {
                 openUrl(this.goodsUrl);
                 setState(() => isVisible = false);
               },
               text: Text("go shopping"),
             ),
      ]));
}