fix: Move Page navigation focus to outer elements if available

src/Uno.UI.RuntimeTests/Tests/Windows_UI_Xaml_Input/Given_FocusManager.cs

@@ -184,7 +184,6 @@ public async Task When_Page_Navigates_Focus_Without_Outer_Wrapper()
 		[TestMethod]
 		[RunsOnUIThread]
 		[RequiresFullWindow]
-		[Ignore("This test only passes on Windows - see #7900")]
 		public async Task When_Page_Navigates_Focus_With_Outer_Before()
 		{
 			var stackPanel = new StackPanel();
@@ -252,7 +251,6 @@ public async Task When_Page_Navigates_Focus_Outside_Frame()
 		[TestMethod]
 		[RunsOnUIThread]
 		[RequiresFullWindow]
-		[Ignore("This test only passes on Windows - see #7900")]
 		public async Task When_Page_Navigates_Focus_With_Outer_After()
 		{
 			var stackPanel = new StackPanel();
@@ -320,7 +318,6 @@ public async Task When_Page_Navigate_Back_Without_Outer_Wrapper()
 		[TestMethod]
 		[RunsOnUIThread]
 		[RequiresFullWindow]
-		[Ignore("This test only passes on Windows - see #7900")]
 		public async Task When_Page_Navigate_Back_With_Outer_Before()
 		{
 			var stackPanel = new StackPanel();
@@ -355,7 +352,6 @@ public async Task When_Page_Navigate_Back_With_Outer_Before()
 		[TestMethod]
 		[RunsOnUIThread]
 		[RequiresFullWindow]
-		[Ignore("This test only passes on Windows - see #7900")]
 		public async Task When_Page_Navigate_Back_With_Outer_After()
 		{
 			var stackPanel = new StackPanel();

src/Uno.UI.RuntimeTests/Tests/Windows_UI_Xaml_Input/TestPages/FocusNavigationPage.cs

@@ -11,6 +11,12 @@ public partial class FocusNavigationPage : Page
 		public FocusNavigationPage()
 		{
 			Loaded += Page_Loaded;
+			Unloaded += Page_Unloaded;
+		}
+
+		private void Page_Unloaded(object sender, Windows.UI.Xaml.RoutedEventArgs e)
+		{
+			_loadingTaskCompletionSource = new TaskCompletionSource<object>();
 		}
 
 		private void Page_Loaded(object sender, Windows.UI.Xaml.RoutedEventArgs e)

src/Uno.UI/UI/Xaml/Controls/Frame/Frame.cs

@@ -357,7 +357,10 @@ private bool InnerNavigateUnsafe(PageStackEntry entry, NavigationMode mode)
 				CurrentEntry.Instance = page;
 			}
 
-			UnfocusCurrentPage();
+			using (var leavingDisposable = MarkCurrentPageLeaving())
+			{
+				MoveFocusFromCurrent();
+			}
 
 			Content = CurrentEntry.Instance;
 
@@ -403,8 +406,6 @@ private bool InnerNavigateUnsafe(PageStackEntry entry, NavigationMode mode)
 
 			Navigated?.Invoke(this, navigationEvent);
 
-			FocusCurrentPage();
-
 			return true;
 		}
 
@@ -463,35 +464,34 @@ private void OnNavigationStopped(PageStackEntry entry, NavigationMode mode)
 					));
 		}
 
-		private void UnfocusCurrentPage()
+		private IDisposable MarkCurrentPageLeaving()
 		{
-			var focusManager = VisualTree.GetFocusManagerForElement(this);
-			if (focusManager?.FocusedElement is not { } focusedElement)
+			if (Content is Page page)
 			{
-				return;
-			}
-
-			var isWithinCurrentPage = focusedElement.GetParents().Any(p => p == this);
-			if (isWithinCurrentPage)
-			{
-				focusManager.ClearFocus();
+				page.IsLeavingFrame = true;
+				return Disposable.Create(() => page.IsLeavingFrame = false);
 			}
+			return Disposable.Empty;
 		}
 
-		private void FocusCurrentPage()
+		private void MoveFocusFromCurrent()
 		{
 			var focusManager = VisualTree.GetFocusManagerForElement(this);
-			if (focusManager is null)
+			if (focusManager?.FocusedElement is not { } focusedElement)
 			{
 				return;
 			}
 
-			var focused = focusManager.FocusedElement;
+			var inCurrentPage = focusedElement.GetParents().Any(p => p == this);
 
-			if (focused is null && Content is Page page)
+			if (inCurrentPage)
 			{
-				// Try to set focus on the page
-				page.TryInitialFocus();
+				// Set the focus on the next focusable element.
+				// If we remove the currently focused element from the live tree, inside a GettingFocus or LosingFocus handler,
+				// we failfast. This is being tracked by Bug 9840123
+				focusManager.SetFocusOnNextFocusableElement(FocusState, true);
+
+				(focusedElement as Control)?.UpdateFocusState(FocusState.Unfocused);
 			}
 		}
 	}

src/Uno.UI/UI/Xaml/Controls/Page/Page.cs

@@ -91,5 +91,7 @@ protected override void OnBackgroundChanged(DependencyPropertyChangedEventArgs e
 		{
 			UpdateBorder();
 		}
+
+		internal bool IsLeavingFrame { get; set; }
 	}
 }

src/Uno.UI/UI/Xaml/Controls/Page/Page.mux.cs

@@ -22,11 +22,6 @@ private protected override void OnLoaded()
 		{
 			base.OnLoaded();
 
-			TryInitialFocus();
-		}
-
-		public void TryInitialFocus()
-		{
 			var spCurrentFocusedElement = this.GetFocusedElement();
 
 			var focusManager = VisualTree.GetFocusManagerForElement(this);
@@ -55,7 +50,7 @@ public void TryInitialFocus()
 					focusManager.InitialFocus = true;
 
 					TrySetFocusedElement(spFirstFocusableElementDO);
-					
+
 					focusManager.InitialFocus = false;
 				}
 

src/Uno.UI/UI/Xaml/UIElement.mux.cs

@@ -104,6 +104,13 @@ internal bool AreAllAncestorsVisible()
 					return false;
 				}
 
+				// TODO Uno specific: IsLeaving is not yet implemented on visual tree level,
+				// so we check if the Page is being navigated away from here instead.
+				if (pNext is Page page && page.IsLeavingFrame) 
+				{
+					return false;
+				}
+
 				pElement = pNext;
 			}