How do I scroll to an off-screen element? ListView.builder uses pagination, and hidden items are not embedded in the tree

Example:

import 'package:flutter/material.dart';

class ScrollView1 extends StatefulWidget {
  @override
  _ScrollView1State createState() => _ScrollView1State();
}

class _ScrollView1State extends State<ScrollView1> {
  final dataKey = new GlobalKey();

  List<String> list1 = [
    'button1',
    'button2',
    'button3',
    'button4',
    'button5',
    'button6',
    'button7'
  ];

  List<GlobalKey> listKey = [];

  List<GlobalKey> listKeyBody = [];

  void addKey() {
    for (var i = 0; i < list1.length; i++) {
      final key = GlobalKey();
      listKey.add(key);
      final key2 = GlobalKey();
      listKeyBody.add(key2);
    }
  }

  @override
  void initState() {
    addKey();
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        children: <Widget>[
          Container(
            height: 100,
            child: ListView.builder(
              shrinkWrap: true,
              scrollDirection: Axis.horizontal,
              itemBuilder: (context, i) {
                return FlatButton(
                  key: listKey[i],
                  child: Text('${list1[i]} - $i ${listKeyBody[i]}'),
                  onPressed: () {
                    Scrollable.ensureVisible(listKeyBody[i].currentContext);
                  },
                );
              },
              itemCount: list1.length,
            ),
          ),
          Expanded(
            child: ListView.builder(
              shrinkWrap: true,
              itemBuilder: (context, i) {
                return Container(
                    key: listKeyBody[i],
                    height: 200,
                    child: Center(
                        child:
                            Text('Hello ${list1[i]} $i - ${listKeyBody[i]}')));
              },
              itemCount: list1.length,
            ),
          ),
        ],
      ),
    );
  }
}