Add initial support for Multiple Windows on MacOS

samples/CommunityToolkit.Maui.Sample/App.xaml.cs

@@ -7,7 +7,24 @@ public partial class App : Application
 	public App()
 	{
 		InitializeComponent();
-
 		MainPage = new AppShell();
 	}
+
+#if MACCATALYST
+	protected override Window CreateWindow(IActivationState? activationState)
+    {
+        Window window = base.CreateWindow(activationState);
+        window.Destroying += (object? sender, EventArgs args) =>
+        {
+            if (Current?.Windows?.Count - 1 == 0) 
+			{
+				// Exit the app when the last window closes
+				// This ensures app closes when last window closes on Mac
+				Environment.Exit(0);
+			}
+        };
+        return window;
+    }
+
+#endif
 }

samples/CommunityToolkit.Maui.Sample/Platforms/MacCatalyst/Info.plist

@@ -24,6 +24,23 @@
 		<string>UIInterfaceOrientationLandscapeLeft</string>
 		<string>UIInterfaceOrientationLandscapeRight</string>
 	</array>
+	<key>UIApplicationSceneManifest</key>
+	<dict>
+	<key>UIApplicationSupportsMultipleScenes</key>
+	<true/>
+	<key>UISceneConfigurations</key>
+	<dict>
+		<key>UIWindowSceneSessionRoleApplication</key>
+		<array>
+		<dict>
+			<key>UISceneConfigurationName</key>
+			<string>__MAUI_DEFAULT_SCENE_CONFIGURATION__</string>
+			<key>UISceneDelegateClassName</key>
+			<string>SceneDelegate</string>
+		</dict>
+		</array>
+	</dict>
+	</dict>
 	<key>XSAppIconAssets</key>
 	<string>Assets.xcassets/appicon.appiconset</string>
 	<key>NSSpeechRecognitionUsageDescription</key>

samples/CommunityToolkit.Maui.Sample/Platforms/MacCatalyst/SceneDelegate.cs

@@ -0,0 +1,12 @@
+using System;
+using Foundation;
+using Microsoft.Maui;
+using ObjCRuntime;
+using UIKit;
+
+namespace CommunityToolkit.Maui.Sample.Platforms.MacCatalyst;
+
+[Register("SceneDelegate")]
+public class SceneDelegate : MauiUISceneDelegate
+{
+}