Flutter中的重叠SliverList子项

import 'package:flutter/material.dart';

CustomScrollView(
  slivers: <Widget>[
    SliverList(
      delegate: SliverChildBuilderDelegate(
        (BuildContext context, int index) {
          // 构建子项
          return Container(
            height: 100,
            color: Colors.blue,
            child: Text('Item $index'),
          );
        },
        childCount: 10,
      ),
    ),
  ],
)

CustomScrollView(
  slivers: <Widget>[
    SliverList(
      delegate: SliverChildBuilderDelegate(
        (BuildContext context, int index) {
          // 构建子项
          return Stack(
            children: <Widget>[
              Container(
                height: 100,
                color: Colors.blue,
                child: Text('Item $index'),
              ),
              Positioned(
                top: 50,
                left: 50,
                child: Container(
                  height: 50,
                  width: 50,
                  color: Colors.red,
                  child: Text('Overlay'),
                ),
              ),
            ],
          );
        },
        childCount: 10,
      ),
    ),
  ],
)