[Windows] Multi-window: buttons stop working when dragging a click from a window to another one #189583

// ignore_for_file: implementation_imports, invalid_use_of_internal_member

import 'dart:io';

import 'package:flutter/material.dart';
import 'package:flutter/src/widgets/_window.dart' as fw;

void main() {
  WidgetsFlutterBinding.ensureInitialized();
  runWidget(const MultiWindowApp());
}

class MultiWindowApp extends StatefulWidget {
  const MultiWindowApp({super.key});

  @override
  State<MultiWindowApp> createState() => _MultiWindowAppState();
}

class _MultiWindowAppState extends State<MultiWindowApp> {
  final fw.RegularWindowController _controller = fw.RegularWindowController(
    size: const Size(800, 600),
    title: 'Main window',
    delegate: _MainWindowDelegate(),
  );

  @override
  Widget build(BuildContext context) {
    return fw.RegularWindow(
      controller: _controller,
      child: const MaterialApp(home: MainWindow()),
    );
  }
}

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

  @override
  Widget build(BuildContext context) {
    final registry = fw.WindowRegistry.of(context);

    return Scaffold(
      body: Center(
        child: FilledButton(
          onPressed: () => openChildWindow(registry),
          child: const Text('Open child window'),
        ),
      ),
    );
  }
}

void openChildWindow(fw.WindowRegistry registry) {
  late final fw.WindowEntry entry;
  final controller = fw.RegularWindowController(
    size: const Size(520, 360),
    title: 'Child window',
    delegate: _ChildWindowDelegate(
      onDestroyed: () => registry.unregister(entry),
    ),
  );

  entry = fw.WindowEntry(
    controller: controller,
    builder: (_) => const MaterialApp(home: ChildWindow()),
  );

  registry.register(entry);
}

class ChildWindow extends StatefulWidget {
  const ChildWindow({super.key});

  @override
  State<ChildWindow> createState() => _ChildWindowState();
}

class _ChildWindowState extends State<ChildWindow> {
  static const colors = [
    Color(0xFFE8F0FF),
    Color(0xFFFFE8E8),
  ];

  Color color = colors[0];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: color,
      body: Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          spacing: 4,
          children: [
            ElevatedButton(
              onPressed: () {
                setState(() {
                  color = colors.firstWhere((c) => c != color);
                });
              },
              child: const Text('Change color'),
            ),
            ElevatedButton(
              onPressed: () {
                setState(() {
                  color = colors.firstWhere((c) => c != color);
                });
              },
              child: const Text('Change color'),
            ),
          ],
        ),
      ),
    );
  }
}

class _MainWindowDelegate with fw.RegularWindowControllerDelegate {
  @override
  void onWindowDestroyed() {
    exit(0);
  }
}

class _ChildWindowDelegate with fw.RegularWindowControllerDelegate {
  const _ChildWindowDelegate({required this.onDestroyed});

  final VoidCallback onDestroyed;

  @override
  void onWindowDestroyed() {
    onDestroyed();
  }
}