class FirstMain extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body:TabviewWidget(),
      drawer: Drawer(

        child: ListView(
          children: <Widget>[

            ListTile(
              title: Text('Item 2'),
              onTap: () {
                Navigator.push(
              context,
              MaterialPageRoute(builder: (context) => SecondRoute()),
            );

              },
            ),
          ],
        ),
      ),

    );

  }
}

class SecondRoute extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Second Route"),
      ),
      body: Center(
        child: RaisedButton(
          onPressed: () {
            Navigator.pop(context);
          },
          child: Text('Go back!'),
        ),
      ),
    );
  }
}