如何在单击时将ExpansionTile小部件覆盖到其他小部件上？

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('ExpansionTile Example'),
        ),
        body: MyHomePage(),
      ),
    );
  }
}

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

class _MyHomePageState extends State<MyHomePage> {
  bool _isExpanded = false;

  @override
  Widget build(BuildContext context) {
    return Stack(
      children: [
        // 其他小部件
        Container(
          color: Colors.grey[200],
          padding: EdgeInsets.all(16),
          child: Text('Other Widgets'),
        ),
        // ExpansionTile 小部件
        Positioned.fill(
          child: GestureDetector(
            onTap: () {
              setState(() {
                _isExpanded = !_isExpanded;
              });
            },
            child: ExpansionTile(
              title: Text('Expand Me'),
              children: [
                ListTile(
                  title: Text('Item 1'),
                ),
                ListTile(
                  title: Text('Item 2'),
                ),
              ],
              expanded: _isExpanded,
            ),
          ),
        ),
      ],
    );
  }
}