Flutter ExpansionTile 二级菜单

代码
class TwoLevelListDemo extends StatelessWidget {
  static const String routeName = '/material/two-level-list';

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Expand/collapse list control'),
        actions: <Widget>[MaterialDemoDocumentationButton(routeName)],
      ),
      body: ListView(
        children: <Widget>[
          const ListTile(title: Text('Top')),
          ExpansionTile(
             title: const Text('Sublist'),
             backgroundColor: Theme.of(context).accentColor.withOpacity(0.025),
             children: const <Widget>[
               ListTile(title: Text('One')),
               ListTile(title: Text('Two')),
               // https://en.wikipedia.org/wiki/Free_Four
               ListTile(title: Text('Free')),
               ListTile(title: Text('Four'))
             ]
          ),
           const ListTile(title: Text('Bottom'))
        ]
      )
    );
  }
}
效果图
image.png