Repository: flutter
Issue: [Windows] Accessibility of dialogs
Labels: framework,f: material design,a: accessibility,platform-windows,a: desktop,has reproducible steps,P2,found in release: 2.10,found in release: 2.13,team-windows,triaged-windows

Hi,
When using the `pushDialog` function with an instance of `AlertDialog` (and probably other `Dialog` instances too), the accessibility leaves a lot to be desired.

#### Code

```dart
import 'package:flutter/material.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 Demo',
      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> {
  int _counter = 0;

  void _incrementCounter(final BuildContext context) {
    showDialog(
        context: context,
        builder: (context) => AlertDialog(
              actions: [
                TextButton(
                  onPressed: () {
                    Navigator.pop(context);
                    setState(() {
                      _counter++;
                    });
                  },
                  child: const Text('OK'),
                )
              ],
              content: Text('Counter: $_counter.'),
            ));
  }

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return Scaffold(
      appBar: AppBar(
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: Text(widget.title),
      ),
      body: Center(
        // Center is a layout widget. It takes a single child and positions it
        // in the middle of the parent.
        child: Column(
          // Column is also a layout widget. It takes a list of children and
          // arranges them vertically. By default, it sizes itself to fit its
          // children horizontally, and tries to be as tall as its parent.
          //
          // Invoke "debug painting" (press "p" in the console, choose the
          // "Toggle Debug Paint" action from the Flutter Inspector in Android
          // Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
          // to see the wireframe for each widget.
          //
          // Column has various properties to control how it sizes itself and
          // how it positions its children. Here we use mainAxisAlignment to
          // center the children vertically; the main axis here is the vertical
          // axis because Columns are vertical (the cross axis would be
          // horizontal).
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            const Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline4,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () => _incrementCounter(context),
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}
```

Under Windows, using NVDA, when I press the button nothing is even spoken until I use the tab key. Same when running with Chrome, also using NVDA.

#### Flutter Doctor

```shell
[ÔêÜ] Flutter (Channel master, 2.13.0-0.0.pre.366, on Microsoft Windows [Version 10.0.22000.556], locale en-GB)
    ÔÇó Flutter version 2.13.0-0.0.pre.366 at C:\Users\chris\flutter
    ÔÇó Upstream repository https://github.com/flutter/flutter.git
    ÔÇó Framework revision 0b97874895 (2 days ago), 2022-04-01 21:20:01 -0400
    ÔÇó Engine revision 801d8c530f
    ÔÇó Dart version 2.17.0 (build 2.17.0-265.0.dev)
    ÔÇó DevTools version 2.12.1

[ÔêÜ] Android toolchain - develop for Android devices (Android SDK version 31.0.0-rc2)
    ÔÇó Android SDK at C:\Users\chris\AppData\Local\Android\sdk
    ÔÇó Platform android-31, build-tools 31.0.0-rc2
    ÔÇó Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
    ÔÇó Java version OpenJDK Runtime Environment (build 11.0.10+0-b96-7249189)
    ÔÇó All Android licenses accepted.

[ÔêÜ] Chrome - develop for the web
    ÔÇó Chrome at C:\Program Files (x86)\Google\Chrome\Application\chrome.exe

[ÔêÜ] Visual Studio - develop for Windows (Visual Studio Enterprise 2022 17.1.0)
    ÔÇó Visual Studio at C:\Program Files\Microsoft Visual Studio\2022\Enterprise
    ÔÇó Visual Studio Enterprise 2022 version 17.1.32210.238
    ÔÇó Windows 10 SDK version 10.0.22000.0

[ÔêÜ] Android Studio (version 2020.3)
    ÔÇó Android Studio at C:\Program Files\Android\Android Studio
    ÔÇó Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    ÔÇó Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart
    ÔÇó Java version OpenJDK Runtime Environment (build 11.0.10+0-b96-7249189)

[ÔêÜ] VS Code, 64-bit edition (version 1.66.0)
    ÔÇó VS Code at C:\Program Files\Microsoft VS Code
    ÔÇó Flutter extension version 3.27.0

[ÔêÜ] Connected device (4 available)
    ÔÇó Windows (desktop)       ÔÇó windows ÔÇó windows-x64     ÔÇó Microsoft Windows [Version 10.0.22000.556]
    ÔÇó Windows (UWP) (desktop) ÔÇó winuwp  ÔÇó windows-uwp-x64 ÔÇó 
    ÔÇó Chrome (web)            ÔÇó chrome  ÔÇó web-javascript  ÔÇó Google Chrome 99.0.4844.84
    ÔÇó Edge (web)              ÔÇó edge    ÔÇó web-javascript  ÔÇó Microsoft Edge 98.0.1108.56

[ÔêÜ] HTTP Host Availability
    ÔÇó All required HTTP hosts are available

ÔÇó No issues found!
```

Thanks in advance.