Flutterでスティッキーヘッダーかつドラッグ＆ドロップ

CustomScrollViewの中に SliverAppBar でスクロールの各タイトル SliverReorderableListを利用した MySliverReorderableList が各項目の中身

import 'package:flutter/material.dart';

class HomeScreen extends StatelessWidget {
  const HomeScreen({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return const Material(
      child: CustomScrollView(
        slivers: [
          SliverAppBar(
            pinned: true,
            title: Text('title1'),
          ),
          MySliverReorderableList(),
          SliverAppBar(
            pinned: true,
            title: Text('title2'),
          ),
          MySliverReorderableList(),
          SliverAppBar(
            pinned: true,
            title: Text('title3'),
          ),
          MySliverReorderableList(),
        ],
      ),
    );
  }
}

class MySliverReorderableList extends StatefulWidget {
  const MySliverReorderableList({
    Key? key,
  }) : super(key: key);

  @override
  State<MySliverReorderableList> createState() =>
      _MySliverReorderableListState();
}

class _MySliverReorderableListState extends State<MySliverReorderableList> {
  final _items = List.generate(
    10,
    (index) => index,
  );

  @override
  Widget build(BuildContext context) {
    return SliverReorderableList(
      itemBuilder: (context, index) {
        return ReorderableDragStartListener(
          key: UniqueKey(),
          index: index,
          child: Material(
            child: DecoratedBox(
              decoration: BoxDecoration(
                  border: Border.all(
                color: Colors.grey,
              )),
              child: ListTile(
                title: Text('Item No.${_items[index]}'),
              ),
            ),
          ),
        );
      },
      itemCount: _items.length,
      onReorder: (oldIndex, newIndex) {
        setState(() {
          if (oldIndex < newIndex) {
            newIndex -= 1;
          }

          final temp = _items[oldIndex];
          _items
            ..removeAt(oldIndex)
            ..insert(newIndex, temp);
        });
      },
    );
  }
}