Open drawer on clicking AppBar

Question

If you create an Scafold there is an option for drawer. If you now create this drawer you get automaticly the menu icon on the leading position of the appbar. But i want an

Answer 1

Alternative to the accepted answer which does not require a GlobalKey:

class _TestState extends State {
  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      drawer: new Drawer(),
      appBar: new AppBar(
        leading: Builder(
        builder: (context) => IconButton(
            icon: new Icon(Icons.settings),
            onPressed: () => Scaffold.of(context).openDrawer(),
          ),
        ),
      ),
    );
  }
}