[Windows] - Fix view position shift when shadows are added or removed at runtime

src/Controls/tests/TestCases.HostApp/Issues/Issue27732.cs

@@ -0,0 +1,105 @@
+using Microsoft.Maui.Controls.Shapes;
+
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 27732, "[Windows] View Position Shifts When Shadows Are Dynamically Removed or Resized", PlatformAffected.UWP)]
+public class Issue27732 : TestContentPage
+{
+	Border borderShadow;
+	Image imageShadow;
+	Label labelShadow;
+	Button shadowButton;
+	bool _shadow = false;
+
+	protected override void Init()
+	{
+		Title = "Issue27732";
+		borderShadow = new Border
+		{
+			AutomationId = "BorderShadow",
+			StrokeShape = new RoundRectangle { CornerRadius = 24 },
+			Background = Colors.Red,
+			WidthRequest = 80
+		};
+
+		imageShadow = new Image
+		{
+			AutomationId = "ImageShadow",
+			Aspect = Aspect.AspectFit,
+			Source = "oasis.jpg",
+			WidthRequest = 80
+		};
+
+		labelShadow = new Label
+		{
+			AutomationId = "LabelShadow",
+			Text = "Label",
+			FontSize = 18,
+			WidthRequest = 80
+		};
+
+		shadowButton = new Button
+		{
+			AutomationId = "ToggleShadowButton",
+			Text = "Add Shadow",
+			HorizontalOptions = LayoutOptions.Start
+		};
+		shadowButton.Clicked += OnShadowClicked;
+
+		Content = new StackLayout
+		{
+			Margin = new Thickness(0, 40),
+			HorizontalOptions = LayoutOptions.Center,
+			Spacing = 20,
+			Children =
+			{
+				new HorizontalStackLayout
+				{
+					HorizontalOptions = LayoutOptions.Center,
+					Spacing = 10,
+					Children = { borderShadow, imageShadow, labelShadow }
+				},
+				new HorizontalStackLayout
+				{
+					Spacing = 10,
+					Children =
+					{
+						new Label
+						{
+							Text = "Toggle Shadow Button:",
+							FontSize = 15,
+							VerticalOptions = LayoutOptions.Center,
+							HorizontalOptions = LayoutOptions.Start
+						},
+						shadowButton
+					}
+				}
+			}
+		};
+	}
+
+	void OnShadowClicked(object sender, EventArgs e)
+	{
+		if (_shadow)
+		{
+			shadowButton.Text = "Add Shadow";
+			borderShadow.Shadow = imageShadow.Shadow = labelShadow.Shadow = null;
+			_shadow = false;
+		}
+		else
+		{
+			shadowButton.Text = "Remove Shadow";
+
+			var newShadow = new Shadow
+			{
+				Brush = Brush.Black,
+				Offset = new Point(4, 4),
+				Radius = 10,
+				Opacity = 0.5f
+			};
+
+			borderShadow.Shadow = imageShadow.Shadow = labelShadow.Shadow = newShadow;
+			_shadow = true;
+		}
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue27732.cs

@@ -0,0 +1,28 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue27732 : _IssuesUITest
+{
+	public Issue27732(TestDevice testDevice) : base(testDevice)
+	{
+	}
+
+	public override string Issue => "[Windows] View Position Shifts When Shadows Are Dynamically Removed or Resized";
+
+	const string ToggleShadowButton = "ToggleShadowButton";
+
+	[Test]
+	[Category(UITestCategories.Visual)]
+	public void ViewShouldNotShiftOnShadowChanged()
+	{
+		App.WaitForElement(ToggleShadowButton);
+		for (int i = 0; i < 5; i++)
+		{
+			App.Tap(ToggleShadowButton);
+		}
+		VerifyScreenshot();
+	}
+}

src/Core/src/Handlers/View/ViewHandlerOfT.Windows.cs

@@ -57,9 +57,9 @@ protected override void RemoveContainer()
 			}
 
 #pragma warning disable RS0030 // Do not use banned APIs; Panel.Children is banned for performance reasons. MauiPanel might not be used everywhere though.
-			var oldParentChildren = PlatformView.Parent is MauiPanel mauiPanel
+			var oldParentChildren = ContainerView.Parent is MauiPanel mauiPanel
 				? mauiPanel.CachedChildren
-				: (PlatformView.Parent as Panel)?.Children;
+				: (ContainerView.Parent as Panel)?.Children;
 #pragma warning restore RS0030 // Do not use banned APIs
 
 			var oldIndex = oldParentChildren?.IndexOf(ContainerView);