main.dart

import 'package:flutter/material.dart';

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

class _MyHomePageState extends State<MyHomePage> with TickerProviderStateMixin {
  final int numTabs = 20;
  TabController tabController;

  @override
  void initState() {
    super.initState();
    tabController = new TabController(initialIndex: 0, length: numTabs, vsync: this);
  }

  @override
  Widget build(BuildContext context) {

    List<Widget> pages = <Widget>[];
    List<Tab> tabs = <Tab>[];
    for (int i = 0; i < numTabs; i++) {
      pages.add(_buildTab(context, i));
      tabs.add(new Tab(text: 'Tab $i'));
    }

    return new Scaffold(
      appBar: new AppBar(
        title: new Text('MyHomePage'),
        bottom: new TabBar(
          controller: tabController,
          tabs: tabs,
          isScrollable: true,
        ),
      ),
      body: new TabBarView(
        //key: new PageStorageKey<String>('TabBarView'),
        controller: tabController,
        children: pages,
      ),
    );
  }

  Widget _buildTab(BuildContext context, int i) {
    return new MyPage(pageNum: i);
  }
}

class MySliverChildDelegate extends SliverChildDelegate {
  MySliverChildDelegate(this.pageNum);
  int pageNum;

  Widget build(BuildContext context, int i) {
    return new ListTile(title: new Text('Page $pageNum ListTile $i'),);
  }

  bool shouldRebuild(MySliverChildDelegate old) {
    return false;
  }
}

class MyPage extends StatefulWidget {
  MyPage({this.pageNum});
  final int pageNum;

  @override
  MyPageState createState() => new MyPageState();
}

class MyPageState extends State<MyPage> {
  ScrollController scrollController;

  @override
  void initState() {
    super.initState();
    scrollController = new ScrollController(keepScrollOffset: true);
  }

  @override
  Widget build(BuildContext context) {
    return new KeyedSubtree(
      key: new PageStorageKey<String>('Page ${widget.pageNum}'),
      child: new RefreshIndicator(
        onRefresh: () async { },
        child: new CustomScrollView(
          controller: scrollController,
          slivers: <Widget>[
            new SliverList(
              delegate: new MySliverChildDelegate(widget.pageNum),
            ),
          ],
        ),
      ),
    );
  }
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return
  }
}

void main() {
  runApp(new MaterialApp(home: new MyHomePage()));
}