How to create a transparent full screen dialog on top of activity - Flutter

Question

I am trying to create a transparent full screen dialog on top of activity. I have tried following this thread but solution doesn\'t work.

In short , what I need

Answer 1

Screenshot (showGeneralDialog):

---

Code:

Widget build(BuildContext context) {
  return Scaffold(
    body: SizedBox.expand(child: FlutterLogo()),
    floatingActionButton: FloatingActionButton(
      child: Icon(Icons.open_in_new),
      onPressed: () {
        showGeneralDialog(
          context: context,
          barrierColor: Colors.black54,
          pageBuilder: (_, __, ___) => Container(child: Material(child: Text('Dialog'))),
        );
      },
    ),
  );
}