MacosWindowUtilsConfig breaks native macOS double-click-to-maximize behavior on latest macOS

[albe-jj]

Description

When applying any MacosWindowUtilsConfig (via macos_ui), the native macOS double-click-to-zoom functionality on the window titlebar stops working. This occurs with all NSWindowToolbarStyle options (unifiedCompact, unified, automatic, expanded), not just specific ones.

This issue only occurs on macOS 26.2 (Tahoe) - the double-click maximize works correctly on previous macOS versions.

The green maximize button still works correctly - only the double-click gesture is broken. with no MacosWindowUtilsConfig also it works correctly.

Steps To Reproduce

1. Create a new Flutter macOS project with flutter create bug
2. Add macos_ui dependency with flutter pub add macos_ui
3. Update main.dart with the code sample below
4. Run the app on macOS with flutter run -d macos
5. Double-click on the window titlebar (the area at the top of the window)
6. Observe that the window does NOT zoom/maximize

Code sample

import 'dart:io';
import 'package:flutter/material.dart';
import 'package:macos_ui/macos_ui.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  if (Platform.isMacOS) {
    // Applying ANY MacosWindowUtilsConfig breaks double-click maximize
    const config = MacosWindowUtilsConfig(
      toolbarStyle: NSWindowToolbarStyle.unifiedCompact,
      // Also broken with: unified, automatic, expanded
    );
    await config.apply();
  }

  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Double-Click Bug Demo',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
      ),
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Double-Click Titlebar Bug'),
        ),
        body: const Center(
          child: Padding(
            padding: EdgeInsets.all(24.0),
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                Text(
                  'Try double-clicking the window titlebar.',
                  style: TextStyle(fontSize: 18),
                ),
                SizedBox(height: 16),
                Text(
                  'Expected: Window should zoom/maximize\n'
                  'Actual: Nothing happens',
                  textAlign: TextAlign.center,
                ),
                SizedBox(height: 24),
                Text(
                  'Note: The green maximize button still works.\n'
                  'Only the double-click gesture is broken.',
                  style: TextStyle(color: Colors.grey),
                  textAlign: TextAlign.center,
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}

Expected behavior

Double-clicking the window titlebar should zoom/maximize the window, which is standard macOS behavior that users expect.

Screenshots

N/A - The bug is that nothing visually happens when double-clicking the titlebar.

Logs

Logs

No errors are logged. The double-click event is simply not triggering the zoom action.

flutter run --verbose output:
(No relevant errors - the app runs normally, just the double-click gesture doesn't work)

flutter analyze output:
(No issues found)

flutter doctor -v output:
(Please run and paste your output here)

Additional Context

• macOS version: 26.2 (Tahoe) - issue does NOT occur on previous macOS versions
• macos_ui version: 2.2.2
• macos_window_utils version: 1.9.1 (transitive dependency)

This issue may be related to the changes in version 2.2.1 combined with changes in macOS 26.2:

"Wrap toolbar items with MacosToolbarPassthrough to prevent window move or resize when interacting with toolbar items"

Workaround

Remove MacosWindowUtilsConfig entirely to restore native double-click behavior:

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  // Don't apply MacosWindowUtilsConfig
  runApp(const MyApp());
}