class MainPage extends StatefulWidget {
  @override
  State createState() {
    return new MainPageState();
  }
}

class MainPageState extends State<MainPage> {
  int _currentIndex = 0;
  List<int> _history = [0];

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text('Bottom Nav Back'),
      ),
      body: new Center(
        child: new Text('Page $_currentIndex'),
      ),
      bottomNavigationBar: new BottomNavigationBar(
        currentIndex: _currentIndex,
        items: <BottomNavigationBarItem>[
          new BottomNavigationBarItem(
            icon: new Icon(Icons.touch_app),
            title: new Text('keypad'),
          ),
          new BottomNavigationBarItem(
            icon: new Icon(Icons.assessment),
            title: new Text('chart'),
          ),
          new BottomNavigationBarItem(
            icon: new Icon(Icons.cloud),
            title: new Text('weather'),
          ),
        ],
        onTap: (int index) {
          _history.add(index);
          setState(() => _currentIndex = index);
          Navigator.push(context, new BottomNavigationRoute()).then((x) {
            _history.removeLast();
            setState(() => _currentIndex = _history.last);
          });
        },
      ),
    );
  }
}

class BottomNavigationRoute extends LocalHistoryRoute<void> {}