Flutter web - Always show horizontal and vertical scrollbar in a DataTable

I have a DataTable and I'm trying to make it always show the horizontal and vertical scrollbars.

I managed to always show the vertical scrollbar, but the horizontal scrollbar only shows when I scroll down to the bottom.

Here's my code:

  final _scrollController = ScrollController();
  final _scrollController2 = ScrollController();

  @override
  Widget build(BuildContext context) {
    return Container(
      height: 300,
      width: 400,
      child: Scrollbar(
        controller: _scrollController,
        isAlwaysShown: true,
        child: SingleChildScrollView(
          controller: _scrollController,
          scrollDirection: Axis.vertical,
          child: Scrollbar(
            controller: _scrollController2,
            isAlwaysShown: true,
            child: SingleChildScrollView(
              controller: _scrollController2,
              scrollDirection: Axis.horizontal,
              child: DataTable(
                showCheckboxColumn: true,
                columns: [
                  DataColumn(
                    label: Text('Name'),
                  ),
                  DataColumn(
                    label: Text('Year'),
                  ),
                  DataColumn(
                    label: Text('Year'),
                  ),
                  DataColumn(
                    label: Text('Year'),
                  ),
                ],
                rows: List<DataRow>.generate(
                  20,
                  (int index) => DataRow(
                    cells: <DataCell>[
                      DataCell(
                        Text('Row $index'),
                      ),
                      DataCell(
                        Text('Row $index'),
                      ),
                      DataCell(
                        Text('Row $index'),
                      ),
                      DataCell(
                        Text('Row $index'),
                      ),
                    ],
                    onSelectChanged: (bool? value) {},
                  ),
                ),
              ),
            ),
          ),
        ),
      ),
    );
  }

I'm using Flutter 2.2.3 (Channel stable).

I tried a lot of things, but I think I finally got it.

here's the final result: Bidirectional scrolling with fixed scrollbar

I used adaptive_scrollbar v2.1.0 to get this result.

Source Code

import 'package:flutter/material.dart';
import 'package:adaptive_scrollbar/adaptive_scrollbar.dart';

void main() {
  runApp(const MyApp());
}

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

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Bidirectional Scrollbars',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({Key? key, required this.title}) : super(key: key);

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    final _verticalScrollController = ScrollController();
    final _horizontalScrollController = ScrollController();

    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Container(
        height: 300,
        width: 700,
        child: AdaptiveScrollbar(
          underColor: Colors.blueGrey.withOpacity(0.3),
          sliderDefaultColor: Colors.grey.withOpacity(0.7),
          sliderActiveColor: Colors.grey,
          controller: _verticalScrollController,
          child: AdaptiveScrollbar(
            controller: _horizontalScrollController,
            position: ScrollbarPosition.bottom,
            underColor: Colors.blueGrey.withOpacity(0.3),
            sliderDefaultColor: Colors.grey.withOpacity(0.7),
            sliderActiveColor: Colors.grey,
            child: SingleChildScrollView(
              controller: _verticalScrollController,
              scrollDirection: Axis.vertical,
              child: SingleChildScrollView(
                controller: _horizontalScrollController,
                scrollDirection: Axis.horizontal,
                child: Padding(
                  padding: const EdgeInsets.only(right: 8.0, bottom: 16.0),
                  child: DataTable(
                    showCheckboxColumn: true,
                    columns: [
                      DataColumn(
                        label: Text('Name'),
                      ),
                      DataColumn(
                        label: Text('Year'),
                      ),
                      DataColumn(
                        label: Text('Year'),
                      ),
                      DataColumn(
                        label: Text('Year'),
                      ),
                      DataColumn(
                        label: Text('Year'),
                      ),
                      DataColumn(
                        label: Text('Name'),
                      ),
                      DataColumn(
                        label: Text('Year'),
                      ),
                      DataColumn(
                        label: Text('Year'),
                      ),
                      DataColumn(
                        label: Text('Year'),
                      ),
                      DataColumn(
                        label: Text('Year'),
                      ),
                    ],
                    rows: List<DataRow>.generate(
                      20,
                      (int index) => DataRow(
                        cells: <DataCell>[
                          DataCell(
                            Text('Row $index'),
                          ),
                          DataCell(
                            Text('Row $index'),
                          ),
                          DataCell(
                            Text('Row $index'),
                          ),
                          DataCell(
                            Text('Row $index'),
                          ),
                          DataCell(
                            Text('Row $index'),
                          ),
                          DataCell(
                            Text('Row $index'),
                          ),
                          DataCell(
                            Text('Row $index'),
                          ),
                          DataCell(
                            Text('Row $index'),
                          ),
                          DataCell(
                            Text('Row $index'),
                          ),
                          DataCell(
                            Text('Row $index'),
                          ),
                        ],
                        onSelectChanged: (bool? value) {},
                      ),
                    ),
                  ),
                ),
              ),
            ),
          ),
        ),
      ),
    );
  }
}