[Windows, Catalyst] Fix IsPresented=true Not Working on Initial Value in FlyoutPage

src/Controls/tests/TestCases.HostApp/Issues/Issue31372.cs

@@ -0,0 +1,59 @@
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 31372, "IsPresented=true Not Working on Initial Value in FlyoutPage", PlatformAffected.UWP | PlatformAffected.macOS)]
+
+public class Issue31372 : NavigationPage
+{
+	public Issue31372()
+	{
+		PushAsync(new Issue31372Page());
+	}
+}
+
+public class Issue31372Page : FlyoutPage
+{
+	public Issue31372Page()
+	{
+
+		// Create Flyout Page
+		var flyoutPage = new ContentPage
+		{
+			Title = "Flyout",
+			Content = new StackLayout
+			{
+				Children =
+				{
+					new Label
+					{
+						Text = "This is Flyout",
+						AutomationId = "FlyoutLabel"
+					}
+				}
+			}
+		};
+
+		// Create Detail Page
+		var detailPage = new ContentPage
+		{
+			Title = "Detailpage",
+			Content = new StackLayout
+			{
+				Padding = 16,
+				Spacing = 16,
+				Children =
+				{
+					new Label
+					{
+						Text = "This is Detail Page which displays additional information."
+					},
+				}
+			}
+		};
+
+		// Assign Flyout and Detail
+		Flyout = flyoutPage;
+		Detail = new NavigationPage(detailPage);
+		FlyoutLayoutBehavior = FlyoutLayoutBehavior.Popover;
+		IsPresented = true;
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue31372.cs

@@ -0,0 +1,22 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues
+{
+	public class Issue31372 : _IssuesUITest
+	{
+		public override string Issue => "IsPresented=true Not Working on Initial Value in FlyoutPage";
+
+		public Issue31372(TestDevice device)
+		: base(device)
+		{ }
+
+		[Test]
+		[Category(UITestCategories.FlyoutPage)]
+		public void VerifyIsPresentedInitialValue()
+		{
+			App.WaitForElement("FlyoutLabel");
+		}
+	}
+}

src/Core/src/Handlers/FlyoutView/FlyoutViewHandler.Windows.cs

@@ -21,12 +21,22 @@ protected override void ConnectHandler(RootNavigationView platformView)
 			_navigationRootManager = MauiContext?.GetNavigationRootManager();
 			platformView.PaneOpened += OnPaneOpened;
 			platformView.PaneClosed += OnPaneClosed;
+			platformView.Loaded += OnLoaded;
+		}
+
+		void OnLoaded(object sender, RoutedEventArgs e)
+		{
+			if (VirtualView is not null)
+			{
+				PlatformView.IsPaneOpen = VirtualView.IsPresented;
+			}
 		}
 
 		protected override void DisconnectHandler(RootNavigationView platformView)
 		{
 			platformView.PaneOpened -= OnPaneOpened;
 			platformView.PaneClosed -= OnPaneClosed;
+			platformView.Loaded -= OnLoaded;
 		}
 
 		void OnPaneOpened(NavigationView sender, object args)

src/Core/src/Handlers/Window/WindowHandler.iOS.cs

@@ -12,9 +12,15 @@ public partial class WindowHandler : ElementHandler<IWindow, UIWindow>
 		protected override void ConnectHandler(UIWindow platformView)
 		{
 			base.ConnectHandler(platformView);
-
+#if MACCATALYST
+			CoreFoundation.DispatchQueue.MainQueue.DispatchAsync(() => 
+			{
+				_frameObserverProxy.Connect(VirtualView, platformView);
+			});
+#else
 			_frameObserverProxy.Connect(VirtualView, platformView);
-
+#endif
+
 			// For newer Mac Catalyst versions, we want to wait until we get effective window dimensions from the platform.
 			if (OperatingSystem.IsMacCatalystVersionAtLeast(16))
 			{