Flutter 保留选项卡视图页面之间的状态

问题

我用TabController在TabBarView里渲染了两个ListViews.

如何将状态(因为没有更好的词)保持在ListView之间，以便:小部件不会重新生成，2.)标签之间会记住ListView的位置.

相关代码

class AppState extends State<App> with SingleTickerProviderStateMixin {
  TabController _tabController;

  @override
  void initState() {
    super.initState();
    _tabController = new TabController(
      vsync: this,
      length: _allPages.length,
    );
  }

  @override
  void dispose() {
    _tabController.dispose();
    super.dispose();
  }

  Widget _buildScaffold(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text('headlines'),
        bottom: new TabBar(
            controller: _tabController,
            isScrollable: true,
            tabs: _allPages
                .map((_Page page) => new Tab(text: page.country))
                .toList()),
      ),
      body: new TabBarView(
          controller: _tabController,
          children: _allPages.map((_Page page) {
            return new SafeArea(
              top: false,
              bottom: false,
              child: new Container(
                key: new ObjectKey(page.country),
                child: new Newsfeed(country: page.country),
              ),
            );
          }).toList()),
    );
  }

  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'news app',
      home: _buildScaffold(context),
    );
  }
}

插图gif

https://media.giphy.com/media/2ysWhzqHVqL1xcBlBE/giphy.gif个