setWindowShouldCloseHandler does not call in MacOS for Flutter SDK 3.22.2.

[brain-5]

Now library not working in MacOS desktop for Flutter SDK 3.22.2, but in Windows and Linux is ok.

% flutter doctor -v
[✓] Flutter version 3.22.2 on channel stable, on macOS 14.5 23F79 darwin-arm64, locale ru-RU
• Upstream repository https://github.com/flutter/flutter.git
• Framework revision 2feea7a407 (2 weeks ago), 2024-06-06 10:19:10 +0700
• Engine revision bb10c54666
• Dart version 3.5.0 (build 3.5.0-180.3.beta)
• DevTools version 2.36.0

[✓] Android toolchain - develop for Android devices (Android SDK version 34.0.0)
• Platform android-34, build-tools 34.0.0
• Java binary at: /Applications/Android Studio.app/Contents/jbr/Contents/Home/bin/java
• Java version OpenJDK Runtime Environment (build 17.0.10+0-17.0.10b1087.21-11609105)
• All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 15.4)
• Xcode at /Applications/Xcode.app/Contents/Developer
• Build 15F31d
• CocoaPods version 1.15.2

[✓] Chrome - develop for the web
• Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2024.1)
• Android Studio at /Applications/Android Studio.app/Contents
• Flutter plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/9212-flutter
• Dart plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/6351-dart
• Java version OpenJDK Runtime Environment (build 17.0.10+0-17.0.10b1087.21-11609105)

[✓] VS Code (version 1.90.1)
• VS Code at /Applications/Visual Studio Code.app/Contents
• Flutter extension version 3.90.0

[✓] Connected device (3 available)
• macOS (desktop) • macos • darwin-arm64 • macOS 14.5 23F79 darwin-arm64
• Mac Designed for iPad (desktop) • mac-designed-for-ipad • darwin • macOS 14.5 23F79 darwin-arm64
• Chrome (web) • chrome • web-javascript • Google Chrome 126.0.6478.62

[✓] Network resources
• All expected network resources are available.

• No issues found!

[PWrzesinski]

For other people that may encounter this issue in the future, Flutter supports the confirm-on-quit functionality natively now: https://api.flutter.dev/flutter/widgets/AppLifecycleListener-class.html

[driftwoodstudio]

@PWrzesinski Note that I tried the native solution, and it "sort of" works. It works if your app initiates close (via code or menu, for example). You get a chance to show a dialog for confirmation.

But it does not work if the user uses the window close button (on Mac) to close the window. Normally, this closes the flutter container window and the app exits. If you register a callback with AppLifecycleListner, the flutter window still closes, the callback listener activates, and... the app is left waiting forever for a "should close?" answer from the code that is trying to show a Confirm dialog. The reason is because the BuildContext used to try to show that dialog is a child of the main flutter window -- the one that just closed and was torn down when the user clicked the red "window close" button on the Mac window.

So the Flutter support only works for things like iOS/android apps, that don't have a window that can be closed.

On Mac, closing the window destroys your Flutter window widget hierarchy, preventing you from displaying any confirm dialog.

[PWrzesinski]

Hello @driftwoodstudio you are right! I'm making an admin panel with this for myself so wasn't testing very carefully and I personally always quit with cmd+q, so didn't notice this. I'm already using the window_manager package elsewhere, which offers the functionality to prevent closing the window, so I fixed this on my part. If you don't want to use this package, it should also be possible to prevent to window from closing by adding an NSWindowDelegate to the MainFlutterWindow on the Swift's side and implementing the windowShouldClose method, but I didn't test it. It's described here: https://pub.dev/documentation/macos_window_utils/latest/macos_ns_window_delegate/NSWindowDelegate-class.html

[driftwoodstudio]

@PWrzesinski Thanks for the comment. I started on that path (working on doing direct native integrations), but then ended up using this instead: window_manager_plus https://pub.dev/packages/flutter_windowmanager_plus

It's an updated extension of the window_manager class, and it solved all my issues. Reliable close detection via menu or platform's window decorations, tested on both Mac and windows. Also using the "set window minimum size" but haven't made use of other features. The base window_manager package had some issues, but this seems to fix it with reliable, solid updates.

Have to make sure to make the platform-specific changes to Xcode and windows source files flutter provides, and have to make sure to invoke your own exit by calling the package's close() methods (vs doing Navigator.pop() on root navigator as flutter generally suggests).

But other than that, I found installation and use to be straightforward, and it solves every test case I could throw at it so far.

[tomekit]

Hi @driftwoodstudio,
Thanks for your suggestion. I've looked at the: https://pub.dev/packages/flutter_windowmanager_plus package and it says Android only.

Are you saying you can actually use it on Windows and macOS as well?

UPDATE: Did you mean this package instead? https://pub.dev/packages/window_manager_plus

[ltOgt]

The window_manager package also seems to do the trick on macos

• https://pub.dev/documentation/window_manager/latest/window_manager/WindowManager/addListener.html
• https://pub.dev/documentation/window_manager/latest/window_manager/WindowManager/setPreventClose.html

{

late final macosCloseListener = _MacosCloseListener(shouldClose: _shouldClose);

Future<bool> _shouldClose() => ... show dialog etc

void _onChangeShouldWarn() {
    final bool shouldNotify = widget.shouldShowWarning;

    if (AppPlatform.isMacOS) {
      WindowManager.instance.setPreventClose(shouldNotify);
      if (shouldNotify) {
        WindowManager.instance.addListener(macosCloseListener);
      } else {
        WindowManager.instance.removeListener(macosCloseListener);
      }
      return;
    }

   ...
  }

}

class _MacosCloseListener with WindowListener {
  final Future<bool> Function() shouldClose;

  _MacosCloseListener({required this.shouldClose});
  @override
  void onWindowClose() async {
    super.onWindowClose();
    final shouldClose = await this.shouldClose();
    if (shouldClose) {
      WindowManager.instance.setPreventClose(false);
      WindowManager.instance.close();
    }
  }
}