[Windows] Fix Shell title bar overlap with window controls in RTL mode

src/Controls/src/Core/Handlers/Shell/ShellHandler.Windows.cs

@@ -1,5 +1,7 @@
 #nullable disable
 using System;
+using System.Runtime.InteropServices;
+using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Maui.Controls.Platform;
 using Microsoft.UI.Xaml;
 using Microsoft.UI.Xaml.Controls;
@@ -12,6 +14,14 @@ namespace Microsoft.Maui.Controls.Handlers
 {
 	public partial class ShellHandler : ViewHandler<Shell, ShellView>
 	{
+		[DllImport("user32.dll", SetLastError = true)]
+		static extern int GetWindowLong(IntPtr hWnd, int nIndex);
+
+		[DllImport("user32.dll", SetLastError = true)]
+		static extern int SetWindowLong(IntPtr hWnd, int nIndex, int dwNewLong);
+
+		const int GWL_EXSTYLE = -20;
+		const int WS_EX_LAYOUTRTL = 0x00400000;
 		ScrollViewer _scrollViewer;
 		double? _topAreaHeight = null;
 		double? _headerHeight = null;
@@ -164,6 +174,23 @@ public static void MapFlyout(ShellHandler handler, IFlyoutView flyoutView)
 		internal static void MapFlowDirection(ShellHandler handler, Shell view)
 		{
 			handler.PlatformView.UpdateFlowDirection(view);
+			var windowRootView = handler.MauiContext?.GetNavigationRootManager()?.RootView as WindowRootView;
+			var window = handler.MauiContext?.Services?.GetService<Microsoft.UI.Xaml.Window>();
+
+			if (window == null)
+				return;
+
+			var hwnd = WinRT.Interop.WindowNative.GetWindowHandle(window);
+			var isRtl = view.FlowDirection == FlowDirection.RightToLeft;
+			var exStyle = GetWindowLong(hwnd, GWL_EXSTYLE);
+
+			// Apply or remove WS_EX_LAYOUTRTL to mirror the window including title bar buttons
+			var newExStyle = isRtl ? (exStyle | WS_EX_LAYOUTRTL) : (exStyle & ~WS_EX_LAYOUTRTL);
+			if (exStyle != newExStyle)
+				SetWindowLong(hwnd, GWL_EXSTYLE, newExStyle);
+
+			if (windowRootView != null)
+				windowRootView.FlowDirection = isRtl ? Microsoft.UI.Xaml.FlowDirection.RightToLeft : Microsoft.UI.Xaml.FlowDirection.LeftToRight;
 		}
 
 		public static void MapIsPresented(ShellHandler handler, IFlyoutView flyoutView)

src/Controls/tests/TestCases.HostApp/Issues/Issue32476.cs

@@ -0,0 +1,59 @@
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 32476, "Binding RTL FlowDirection in Shell causes Flyout MenuIcon and native window controls to overlap", PlatformAffected.UWP)]
+public class Issue32476 : Shell
+{
+	public Issue32476()
+	{
+		FlyoutBehavior = FlyoutBehavior.Flyout;
+		var button = new Button
+		{
+			Text = "Toggle FlowDirection to RTL",
+			AutomationId = "ToggleButton"
+		};
+
+		var buttonTapLabel = new Label
+		{
+			Text = "Tap the button to toggle FlowDirection to RTL",
+			HorizontalOptions = LayoutOptions.Center
+		};
+
+		button.Clicked += (s, e) =>
+		{
+			buttonTapLabel.Text = "Toggling FlowDirection...";
+			FlowDirection = FlowDirection.RightToLeft;
+			buttonTapLabel.Text = "FlowDirection is now RTL";
+		};
+
+		var contentPage = new ContentPage
+		{
+			Content = new VerticalStackLayout
+			{
+				Padding = 20,
+				Spacing = 10,
+				Children =
+					{
+						new Label
+						{
+							Text = "Tap the button to toggle FlowDirection to RTL. The Flyout MenuIcon must not overlap with native window controls.",
+							LineBreakMode = LineBreakMode.WordWrap
+						},
+						button,
+						buttonTapLabel
+					}
+			}
+		};
+		Items.Add(new FlyoutItem
+		{
+			Title = "Home",
+			Items =
+				{
+					new ShellContent
+					{
+						Title = "Main",
+						Content = contentPage
+					}
+				}
+		});
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue32476.cs

@@ -0,0 +1,26 @@
+#if MACCATALYST || WINDOWS  // Native window controls (minimize, maximize, close) are applicable only on Windows and MacCatalyst
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue32476 : _IssuesUITest
+{
+	public Issue32476(TestDevice testDevice) : base(testDevice)
+	{
+	}
+	public override string Issue => "Binding RTL FlowDirection in Shell causes Flyout MenuIcon and native window controls to overlap";
+	[Test]
+	[Category(UITestCategories.Shell)]
+	public void ShellRTLFlowDirectionShouldNotCauseOverlap()
+	{
+		App.WaitForElement("ToggleButton");
+		App.Tap("ToggleButton");
+		App.Tap("ToggleButton");
+
+		// wait for window layout to update after flow direction change.
+		Task.Delay(500).Wait();
+		VerifyScreenshot(includeTitleBar: true);
+	}
+}
+#endif