Refactor window example to use MaterialApp per window

Replaces the global MyApp widget with individual MaterialApp instances for each window (Primary, Secondary, Tertiary). This change improves window isolation and ensures each window has its own navigation and theming context.

Author: lijy91

examples/multiple_window_example/lib/main.dart

@@ -11,25 +11,11 @@ void main() {
   WindowManager.instance.setWillHideHook((windowId) {
     print('Window $windowId will hide');
   });
-  runApp(const MyApp());
-}
-
-class MyApp extends StatelessWidget {
-  const MyApp({super.key});
-
-  // This widget is the root of your application.
-  @override
-  Widget build(BuildContext context) {
-    return MaterialApp(
-      title: 'Multiple Window Example',
-      theme: ThemeData(
-        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
-      ),
-      home: ViewCollection(
-        views: [TertiaryWindow(), SecondaryWindow(), PrimaryWindow()],
-      ),
-    );
-  }
+  runWidget(
+    ViewCollection(
+      views: [TertiaryWindow(), SecondaryWindow(), PrimaryWindow()],
+    ),
+  );
 }
 
 class PrimaryWindow extends StatefulWidget {
@@ -49,29 +35,32 @@ class _PrimaryWindowState extends State<PrimaryWindow> {
   Widget build(BuildContext context) {
     return RegularWindow(
       controller: _windowController,
-      child: Scaffold(
-        appBar: AppBar(title: const Text('Primary Window')),
-        body: Center(
-          child: Column(
-            children: [
-              FilledButton(
-                onPressed: () {
-                  Window? primaryWindow;
-                  final windows = WindowManager.instance.getAll();
-                  for (var window in windows) {
-                    if (window.title == 'Primary Window') {
-                      primaryWindow = window;
-                      break;
+      child: MaterialApp(
+        title: 'Primary Window',
+        home: Scaffold(
+          appBar: AppBar(title: const Text('Primary Window')),
+          body: Center(
+            child: Column(
+              children: [
+                FilledButton(
+                  onPressed: () {
+                    Window? primaryWindow;
+                    final windows = WindowManager.instance.getAll();
+                    for (var window in windows) {
+                      if (window.title == 'Primary Window') {
+                        primaryWindow = window;
+                        break;
+                      }
                     }
-                  }
-                  if (primaryWindow != null) {
-                    primaryWindow.setSize(1000, 1000);
-                    primaryWindow.show();
-                  }
-                },
-                child: const Text('A Window'),
-              ),
-            ],
+                    if (primaryWindow != null) {
+                      primaryWindow.setSize(1000, 1000);
+                      primaryWindow.show();
+                    }
+                  },
+                  child: const Text('A Window'),
+                ),
+              ],
+            ),
           ),
         ),
       ),
@@ -96,9 +85,12 @@ class _SecondaryWindowState extends State<SecondaryWindow> {
   Widget build(BuildContext context) {
     return RegularWindow(
       controller: _windowController,
-      child: Scaffold(
-        appBar: AppBar(title: const Text('Secondary Window')),
-        body: const Center(child: Text('Secondary Window')),
+      child: MaterialApp(
+        title: 'Secondary Window',
+        home: Scaffold(
+          appBar: AppBar(title: const Text('Secondary Window')),
+          body: const Center(child: Text('Secondary Window')),
+        ),
       ),
     );
   }
@@ -121,9 +113,12 @@ class _TertiaryWindowState extends State<TertiaryWindow> {
   Widget build(BuildContext context) {
     return RegularWindow(
       controller: _windowController,
-      child: Scaffold(
-        appBar: AppBar(title: const Text('Tertiary Window')),
-        body: const Center(child: Text('Tertiary Window')),
+      child: MaterialApp(
+        title: 'Tertiary Window',
+        home: Scaffold(
+          appBar: AppBar(title: const Text('Tertiary Window')),
+          body: const Center(child: Text('Tertiary Window')),
+        ),
       ),
     );
   }