在我转到另一个有状态的小部件后，如何将汉堡图标保留在我的flutter应用程序中？

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  final GlobalKey<NavigatorState> _navigatorKey = GlobalKey<NavigatorState>();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Home Page'),
        leading: IconButton(
          icon: Icon(Icons.menu),
          onPressed: () {
            _navigatorKey.currentState!.openDrawer();
          },
        ),
      ),
      drawer: Drawer(
        child: ListView(
          padding: EdgeInsets.zero,
          children: <Widget>[
            DrawerHeader(
              child: Text('Drawer Header'),
              decoration: BoxDecoration(
                color: Colors.blue,
              ),
            ),
            ListTile(
              title: Text('Page 1'),
              onTap: () {
                Navigator.of(context).push(MaterialPageRoute(builder: (context) => Page1()));
              },
            ),
            ListTile(
              title: Text('Page 2'),
              onTap: () {
                Navigator.of(context).push(MaterialPageRoute(builder: (context) => Page2()));
              },
            ),
          ],
        ),
      ),
      body: Center(
        child: ElevatedButton(
          onPressed: () {
            Navigator.of(context).push(MaterialPageRoute(builder: (context) => Page1()));
          },
          child: Text('Go to Page 1'),
        ),
      ),
    );
  }
}

class Page1 extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Page 1'),
        leading: IconButton(
          icon: Icon(Icons.menu),
          onPressed: () {
            Navigator.of(context).pop();
          },
        ),
      ),
      body: Center(
        child: Text('This is Page 1'),
      ),
    );
  }
}

class Page2 extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Page 2'),
        leading: IconButton(
          icon: Icon(Icons.menu),
          onPressed: () {
            Navigator.of(context).pop();
          },
        ),
      ),
      body: Center(
        child: Text('This is Page 2'),
      ),
    );
  }
}