Resolve some life cycle issues with TabbedPage when nested inside a NavigationPage

src/Compatibility/Core/src/Android/AppCompat/FlyoutPageContainer.cs

@@ -222,7 +222,7 @@ protected override void Dispose(bool disposing)
 
 			if (disposing)
 			{
-				if (_currentFragment != null && !FragmentManager.IsDestroyed)
+				if (_currentFragment != null && !FragmentManager.IsDestroyed(Context))
 				{
 					FragmentTransaction transaction = FragmentManager.BeginTransactionEx();
 					transaction.RemoveEx(_currentFragment);

src/Compatibility/Core/src/Android/AppCompat/FormsFragmentPagerAdapter.cs

@@ -84,7 +84,7 @@ protected override void Dispose(bool disposing)
 
 				_page = null;
 
-				if (!_fragmentManager.IsDestroyed)
+				if (!_fragmentManager.IsDestroyed(_page?.Handler?.MauiContext?.Context))
 				{
 					FragmentTransaction transaction = _fragmentManager.BeginTransactionEx();
 

src/Controls/samples/Controls.Sample/Pages/Compatibility/TabbedPageGallery.xaml

@@ -3,16 +3,9 @@
     xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
     xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
     x:Class="Maui.Controls.Sample.Pages.TabbedPageGallery"
+    xmlns:views="clr-namespace:Maui.Controls.Sample.Pages"
     Title="Tabbed Page">
-    <ContentPage Title="Tab 1">
-        <VerticalStackLayout>
-            <Button Text="Set Tabbed Page as Root" Clicked="OnTabbedPageAsRoot"></Button>
-            <Button Text="Toggle Bottom Tabs (Android)" Clicked="OnSetToBottomTabs"></Button>
-            <Button Text="Change Tab Index" Clicked="OnChangeTabIndex"></Button>
-            <Button Text="Toggle TabBar Background Color" Clicked="OnToggleTabBar"></Button>
-            <Button Text="Toggle TabBar Text Color" Clicked="OnToggleTabBarTextColor"></Button>
-            <Button Text="Toggle Tab Item Selected" Clicked="OnToggleTabItemSelectedColor"></Button>
-            <Button Text="Toggle Tab Item UnselectedColor" Clicked="OnToggleTabItemUnSelectedColor"></Button>
-        </VerticalStackLayout>
-    </ContentPage>
+
+    <views:TabbedPageGalleryMainPage></views:TabbedPageGalleryMainPage>
+
 </TabbedPage>

src/Controls/samples/Controls.Sample/Pages/Compatibility/TabbedPageGallery.xaml.cs

@@ -14,77 +14,5 @@ public TabbedPageGallery()
 			this.Children.Add(new NavigationGallery());
 			this.Children.Add(new NavigationPage(new NavigationGallery()) { Title = "With Nav Page" });
 		}
-
-		void OnTabbedPageAsRoot(object sender, EventArgs e)
-		{
-			var topTabs =
-				new TabbedPage()
-				{
-					Children =
-					{
-						Handler.MauiContext.Services.GetRequiredService<Page>(),
-						new NavigationPage(new Pages.NavigationGallery()) { Title = "Navigation Gallery" }
-					}
-				};
-
-			this.Handler?.DisconnectHandler();
-			Application.Current.MainPage?.Handler?.DisconnectHandler();
-			Application.Current.MainPage = topTabs;
-		}
-
-		void OnSetToBottomTabs(object sender, EventArgs e)
-		{
-			var bottomTabs = new TabbedPage()
-			{
-				Children =
-				{
-					Handler.MauiContext.Services.GetRequiredService<Page>(),
-					new NavigationPage(new Pages.NavigationGallery()) { Title = "Navigation Gallery" }
-				}
-			};
-
-			this.Handler?.DisconnectHandler();
-			Application.Current.MainPage?.Handler?.DisconnectHandler();
-
-			AndroidSpecific.TabbedPage.SetToolbarPlacement(bottomTabs, AndroidSpecific.ToolbarPlacement.Bottom);
-			Application.Current.MainPage = bottomTabs;
-		}
-
-		void OnChangeTabIndex(object sender, EventArgs e)
-		{
-			CurrentPage = Children[1];
-		}
-
-		void OnToggleTabBar(object sender, EventArgs e)
-		{
-			if ((this.BarBackground as SolidColorBrush)?.Color == SolidColorBrush.Purple.Color)
-				this.BarBackground = null;
-			else
-				this.BarBackground = SolidColorBrush.Purple;
-		}
-
-		void OnToggleTabBarTextColor(object sender, EventArgs e)
-		{
-			if (this.BarTextColor == Colors.Green)
-				this.BarTextColor = null;
-			else
-				this.BarTextColor = Colors.Green;
-		}
-
-		void OnToggleTabItemUnSelectedColor(object sender, EventArgs e)
-		{
-			if (this.UnselectedTabColor == Colors.Blue)
-				this.UnselectedTabColor = null;
-			else
-				this.UnselectedTabColor = Colors.Blue;
-		}
-
-		void OnToggleTabItemSelectedColor(object sender, EventArgs e)
-		{
-			if (this.SelectedTabColor == Colors.Pink)
-				this.SelectedTabColor = null;
-			else
-				this.SelectedTabColor = Colors.Pink;
-		}
 	}
 }

src/Controls/samples/Controls.Sample/Pages/Compatibility/TabbedPageGalleryMainPage.xaml

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage Title="Tab 1"
+    xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+    x:Class="Maui.Controls.Sample.Pages.TabbedPageGalleryMainPage">
+    <ScrollView>
+        <VerticalStackLayout>
+            <Button Text="Set Tabbed Page as Root" Clicked="OnTabbedPageAsRoot"></Button>
+            <Button Text="Toggle Bottom Tabs (Android)" Clicked="OnSetToBottomTabs"></Button>
+            <Button Text="Change Tab Index" Clicked="OnChangeTabIndex"></Button>
+            <Button Text="Toggle TabBar Background Color" Clicked="OnToggleTabBar"></Button>
+            <Button Text="Toggle TabBar Text Color" Clicked="OnToggleTabBarTextColor"></Button>
+            <Button Text="Toggle Tab Item Selected" Clicked="OnToggleTabItemSelectedColor"></Button>
+            <Button Text="Toggle Tab Item UnselectedColor" Clicked="OnToggleTabItemUnSelectedColor"></Button>
+            <Button Text="Add Tab" Clicked="OnAddTab"></Button>
+            <Button Text="Remove Tab" Clicked="OnRemoveTab"></Button>
+            <Button Text="Remove All New Tabs" Clicked="OnRemoveAllTabs"></Button>
+        </VerticalStackLayout>
+    </ScrollView>
+</ContentPage>

src/Controls/samples/Controls.Sample/Pages/Compatibility/TabbedPageGalleryMainPage.xaml.cs

@@ -0,0 +1,116 @@
+using System;
+using System.Linq;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Maui.Controls;
+using Microsoft.Maui.Graphics;
+using AndroidSpecific = Microsoft.Maui.Controls.PlatformConfiguration.AndroidSpecific;
+
+namespace Maui.Controls.Sample.Pages
+{
+	public partial class TabbedPageGalleryMainPage
+	{
+		public TabbedPageGalleryMainPage()
+		{
+			InitializeComponent();
+		}
+
+		TabbedPage _tabbedPage;
+		TabbedPage GetTabbedPage() => _tabbedPage ??= (TabbedPage)Parent;
+
+		void SetNewMainPage(Page page)
+		{
+			Application.Current.Windows[0].Page = page;
+		}
+
+		void OnTabbedPageAsRoot(object sender, EventArgs e)
+		{
+			var topTabs =
+				new TabbedPage()
+				{
+					Children =
+					{
+						Handler.MauiContext.Services.GetRequiredService<Page>(),
+						new NavigationPage(new Pages.NavigationGallery()) { Title = "Navigation Gallery" }
+					}
+				};
+
+			SetNewMainPage(topTabs);
+		}
+
+		void OnSetToBottomTabs(object sender, EventArgs e)
+		{
+			var bottomTabs = new TabbedPage()
+			{
+				Children =
+				{
+					Handler.MauiContext.Services.GetRequiredService<Page>(),
+					new NavigationPage(new Pages.NavigationGallery()) { Title = "Navigation Gallery" }
+				}
+			};
+
+			SetNewMainPage(bottomTabs);
+			AndroidSpecific.TabbedPage.SetToolbarPlacement(bottomTabs, AndroidSpecific.ToolbarPlacement.Bottom);
+			Application.Current.MainPage = bottomTabs;
+		}
+
+		void OnChangeTabIndex(object sender, EventArgs e)
+		{
+			GetTabbedPage().CurrentPage = GetTabbedPage().Children[1];
+		}
+
+		void OnToggleTabBar(object sender, EventArgs e)
+		{
+			if ((GetTabbedPage().BarBackground as SolidColorBrush)?.Color == SolidColorBrush.Purple.Color)
+				GetTabbedPage().BarBackground = null;
+			else
+				GetTabbedPage().BarBackground = SolidColorBrush.Purple;
+		}
+
+		void OnToggleTabBarTextColor(object sender, EventArgs e)
+		{
+			if (GetTabbedPage().BarTextColor == Colors.Green)
+				GetTabbedPage().BarTextColor = null;
+			else
+				GetTabbedPage().BarTextColor = Colors.Green;
+		}
+
+		void OnToggleTabItemUnSelectedColor(object sender, EventArgs e)
+		{
+			if (GetTabbedPage().UnselectedTabColor == Colors.Blue)
+				GetTabbedPage().UnselectedTabColor = null;
+			else
+				GetTabbedPage().UnselectedTabColor = Colors.Blue;
+		}
+
+		void OnToggleTabItemSelectedColor(object sender, EventArgs e)
+		{
+			if (GetTabbedPage().SelectedTabColor == Colors.Pink)
+				GetTabbedPage().SelectedTabColor = null;
+			else
+				GetTabbedPage().SelectedTabColor = Colors.Pink;
+		}
+
+		void OnRemoveTab(object sender, EventArgs e)
+		{
+			if (GetTabbedPage().Children.LastOrDefault() is TabbedPageGalleryMainPage mainPage)
+			{
+				GetTabbedPage().Children.Remove(mainPage);
+			}
+		}
+
+		void OnRemoveAllTabs(object sender, EventArgs e)
+		{
+			while (GetTabbedPage().Children.LastOrDefault() is TabbedPageGalleryMainPage mainPage)
+			{
+				GetTabbedPage().Children.Remove(mainPage);
+			}
+		}
+
+		void OnAddTab(object sender, EventArgs e)
+		{
+			GetTabbedPage()
+				.Children
+				.Add(new TabbedPageGalleryMainPage() { Title = $"Tab {GetTabbedPage().Children.Count}" });
+		}
+	}
+}

src/Controls/src/Core/Compatibility/Handlers/Shell/Android/ShellFragmentContainer.cs

@@ -23,32 +23,9 @@ public ShellFragmentContainer(ShellContent shellContent, IMauiContext mauiContex
 		public override AView OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
 		{
 			_page = ((IShellContentController)ShellContentTab).GetOrCreateContent();
+			_page.ToPlatform(_mauiContext, RequireContext(), inflater, ChildFragmentManager);
 
-			IMauiContext mauiContext = null;
-
-			// If the page has already been created with a handler then we just let it retain the same
-			// Handler and MauiContext
-			// But we want to update the inflater and ChildFragmentManager to match
-			// the handlers new home			
-			if (_page.Handler?.MauiContext is MauiContext scopedMauiContext)
-			{
-				// If this page comes to us from a different activity then don't reuse it
-				// disconnect the handler so it can recreate against new MauiContext
-				if (scopedMauiContext.GetActivity() == Context.GetActivity())
-				{
-					scopedMauiContext.AddWeakSpecific(ChildFragmentManager);
-					scopedMauiContext.AddWeakSpecific(inflater);
-					mauiContext = scopedMauiContext;
-				}
-				else
-				{
-					_page.Handler.DisconnectHandler();
-				}
-			}
-
-			mauiContext ??= _mauiContext.MakeScoped(layoutInflater: inflater, fragmentManager: ChildFragmentManager);
-
-			return new ShellPageContainer(RequireContext(), (IPlatformViewHandler)_page.ToHandler(mauiContext), true)
+			return new ShellPageContainer(RequireContext(), (IPlatformViewHandler)_page.Handler, true)
 			{
 				LayoutParameters = new LP(LP.MatchParent, LP.MatchParent)
 			};

src/Controls/src/Core/HandlerImpl/NavigationPage/NavigationPage.Impl.cs

@@ -181,32 +181,36 @@ async Task SendHandlerUpdateAsync(
 				// Wait for pending navigation tasks to finish
 				await SemaphoreSlim.WaitAsync();
 
-				var currentNavRequestTaskSource = new TaskCompletionSource<object>();
-				_allPendingNavigationCompletionSource ??= new TaskCompletionSource<object>();
-
-				if (CurrentNavigationTask == null)
-				{
-					CurrentNavigationTask = _allPendingNavigationCompletionSource.Task;
-				}
-				else if (CurrentNavigationTask != _allPendingNavigationCompletionSource.Task)
+				// If our handler was removed while waiting then don't do anything
+				if (Handler != null)
 				{
-					throw new InvalidOperationException("Pending Navigations still processing");
-				}
+					var currentNavRequestTaskSource = new TaskCompletionSource<object>();
+					_allPendingNavigationCompletionSource ??= new TaskCompletionSource<object>();
 
-				_currentNavigationCompletionSource = currentNavRequestTaskSource;
+					if (CurrentNavigationTask == null)
+					{
+						CurrentNavigationTask = _allPendingNavigationCompletionSource.Task;
+					}
+					else if (CurrentNavigationTask != _allPendingNavigationCompletionSource.Task)
+					{
+						throw new InvalidOperationException("Pending Navigations still processing");
+					}
+
+					_currentNavigationCompletionSource = currentNavRequestTaskSource;
 
-				// We create a new list to send to the handler because the structure backing 
-				// The Navigation stack isn't immutable
-				var immutableNavigationStack = new List<IView>(NavigationStack);
-				firePostNavigatingEvents?.Invoke();
+					// We create a new list to send to the handler because the structure backing 
+					// The Navigation stack isn't immutable
+					var immutableNavigationStack = new List<IView>(NavigationStack);
+					firePostNavigatingEvents?.Invoke();
 
-				// Create the request for the handler
-				var request = new NavigationRequest(immutableNavigationStack, animated);
-				((IStackNavigation)this).RequestNavigation(request);
+					// Create the request for the handler
+					var request = new NavigationRequest(immutableNavigationStack, animated);
+					((IStackNavigation)this).RequestNavigation(request);
 
-				// Wait for the handler to finish processing the navigation
-				// This task completes once the handler calls INavigationView.Finished
-				await currentNavRequestTaskSource.Task;
+					// Wait for the handler to finish processing the navigation
+					// This task completes once the handler calls INavigationView.Finished
+					await currentNavRequestTaskSource.Task;
+				}
 			}
 			finally
 			{
@@ -245,6 +249,13 @@ private protected override void OnHandlerChangedCore()
 				})
 				.FireAndForget(Handler);
 			}
+
+			// If the handler is disconnected and we're still waiting for updates from the handler
+			// Just complete any waits
+			if (Handler == null && _waitingCount > 0)
+			{
+				((IStackNavigation)this).NavigationFinished(this.NavigationStack);
+			}
 		}
 
 		// Once we get all platforms over to the new APIs