[Windows] Fix for issues caused by setting Shell.FlyoutWidth on WinUI when binding context values are changed (#27151)

* Fixed FlyoutItem issue

* Fixed Flyout Issues.

* Added test case.

* Added snapshot for WinUI and Mac

* Revert changes

Author: Tamilarasan-Paranthaman

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

@@ -128,15 +128,16 @@ void ShellElementPropertyChanged(object sender, PropertyChangedEventArgs e)
 
 		protected override global::Windows.Foundation.Size ArrangeOverride(global::Windows.Foundation.Size finalSize)
 		{
+			base.ArrangeOverride(finalSize);
+
 			// Replaced ActualWidth with finalSize.Width since ActualWidth updates only after ArrangeOverride completes, 
 			// ensuring accurate layout during the initial arrangement phase.
 			if (finalSize.Width > 0 && _content is IView view)
 			{
 				view.Arrange(new Rect(0, 0, finalSize.Width, finalSize.Height));
-				return finalSize;
 			}
 
-			return base.ArrangeOverride(finalSize);
+			return finalSize;
 		}
 
 		void UpdateVisualState()

src/Controls/tests/TestCases.Android.Tests/snapshots/android/FlyoutItemTextShouldDisplayProperly.png

@@ -0,0 +1,46 @@
+namespace Maui.Controls.Sample.Issues
+{
+	[Issue(IssueTracker.Github, 19496, "The Shell item text disappears when it is updated dynamically at runtime", PlatformAffected.UWP)]
+	public partial class Issue19496 : TestShell
+	{
+		int count = 0;
+		protected override void Init()
+		{
+			FlyoutBackgroundColor = Colors.Gray;
+			FlyoutWidth = 85;
+			FlyoutBehavior = FlyoutBehavior.Locked;
+
+			Label label = new Label
+			{
+				Text = count.ToString(),
+				AutomationId = "FlyoutItemLabel",
+				TextColor = Colors.White
+			};
+
+			ContentPage contentPage = new ContentPage();
+
+			contentPage.Content = new Button()
+			{
+				Text = "Update Label Text",
+				AutomationId = "button",
+				HorizontalOptions = LayoutOptions.Center,
+				VerticalOptions = LayoutOptions.Center,
+				Command = new Command(() =>
+				{
+					count++;
+					label.Text = count.ToString();
+				})
+			};
+
+			DataTemplate dataTemplate = new DataTemplate(() =>
+			{
+
+				return label;
+			});
+
+			this.ItemTemplate = dataTemplate;
+
+			base.AddFlyoutItem(contentPage, "MainPage");
+		}
+	}
+}

src/Controls/tests/TestCases.HostApp/Issues/Issue19496.cs

@@ -0,0 +1,27 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues
+{
+	public class Issue19496 : _IssuesUITest
+	{
+		public override string Issue => "The Shell item text disappears when it is updated dynamically at runtime";
+
+		public Issue19496(TestDevice device)
+		: base(device)
+		{ }
+
+		[Test]
+		[Category(UITestCategories.Shell)]
+		public void FlyoutItemTextShouldDisplayProperly()
+		{
+			App.WaitForElement("button");
+			App.Tap("button");
+			App.Tap("button");
+			App.Tap("button");
+			App.Tap("button");
+			VerifyScreenshot();
+		}
+	}
+}