Flutter: SnackBar inside Dismissible小部件工作不正常

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('My App'),
      ),
      body: ListView.builder(
        itemCount: 5,
        itemBuilder: (context, index) {
          return Dismissible(
            key: Key(index.toString()),
            onDismissed: (direction) {
              // 删除项目的操作
            },
            child: ListTile(
              title: Text('Item $index'),
            ),
          );
        },
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          ScaffoldMessenger.of(context).showSnackBar(
            SnackBar(
              content: Text('SnackBar Message'),
            ),
          );
        },
        child: Icon(Icons.add),
      ),
    );
  }
}