flutter - Flutter web，SliverAppBar浮动不起作用

Question

我试图在颤动的 web 上有一个浮动的 SliverAppBar，但是只有当我滚动到屏幕顶部时才会显示 SliverAppBar。它在 Android 上运行良好。我的代码是：

return Scaffold(
        backgroundColor: Colors.grey[100],
        body: CustomScrollView(slivers: <Widget>[
          SliverAppBar(
            automaticallyImplyLeading: false,
            actions: <Widget>[Container()],
            floating: true,
            title: Text(('My Title')),
            elevation: 0,
          ),
          SliverList(
            delegate: SliverChildListDelegate(
              [
                Container(color: Colors.red, height: 150.0),
                Container(color: Colors.purple, height: 150.0),
                Container(color: Colors.green, height: 150.0),
                Container(color: Colors.red, height: 150.0),
                Container(color: Colors.purple, height: 150.0),
                Container(color: Colors.green, height: 150.0),
                Container(color: Colors.red, height: 150.0),
                Container(color: Colors.purple, height: 150.0),
                Container(color: Colors.green, height: 150.0),
                Container(color: Colors.red, height: 150.0),
                Container(color: Colors.purple, height: 150.0),
                Container(color: Colors.green, height: 150.0),
              ],
            ),
          )
        ]));