Fix page swap from background

src/Controls/samples/Controls.Sample.UITests/Issues/Issue11501.cs

@@ -0,0 +1,183 @@
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.Maui.Controls;
+
+namespace Maui.Controls.Sample.Issues
+{
+	[Issue(IssueTracker.Github, 11501, "Making Fragment Changes While App is Backgrounded Fails", PlatformAffected.Android)]
+	public class Issue11501 : TestContentPage
+	{
+		Func<Task> _currentTest;
+		Page _mainPage;
+		List<Page> _modalStack;
+		Window _window;
+		public Issue11501()
+		{
+			Loaded += OnLoaded;
+		}
+
+		private void OnLoaded(object sender, EventArgs e)
+		{
+			_window = Window;
+			_mainPage = Application.Current.MainPage;
+			_modalStack = Navigation.ModalStack.ToList();
+		}
+
+		private async void OnWindowActivated(object sender, EventArgs e)
+		{
+			DisconnectFromWindow();
+			if (_currentTest is not null)
+			{
+				await Task.Yield();
+				await _currentTest();
+				_currentTest = null;
+			}
+		}
+
+		void ConnectToWindow()
+		{
+			_window.Stopped -= OnWindowActivated;
+			_window.Stopped += OnWindowActivated;
+		}
+
+		void DisconnectFromWindow()
+		{
+			_window.Stopped -= OnWindowActivated;
+		}
+
+		protected override void Init()
+		{
+			Content = new VerticalStackLayout()
+			{
+				new Button()
+				{
+					Text = "Swap Main Page",
+					AutomationId = "SwapMainPage",
+					Command = new Command( () =>
+					{
+						Application.Current.MainPage =
+							new ContentPage() { Title = "Test", Content = new Label() { AutomationId = "BackgroundMe", Text = "Background/Minimize the app" } };
+
+						ConnectToWindow();
+						_currentTest = () =>
+						{
+							Application.Current.MainPage = CreateDestinationPage();
+							return Task.CompletedTask;
+						};
+					})
+				},
+				new Button()
+				{
+					Text = "Changing Details/Flyout on FlyoutPage in Background",
+					AutomationId = "SwapFlyoutPage",
+					Command = new Command(()=>
+					{
+						var flyoutPage = new FlyoutPage()
+						{
+							Flyout = new ContentPage() { Title = "Test", Content = new Label(){Text = "Background/Minimize the app" } },
+							Detail = new NavigationPage(new ContentPage(){ Title = "Test", Content = new Label() { AutomationId = "BackgroundMe", Text = "Background/Minimize the app" } })
+							{
+								Title = "Test"
+							},
+						};
+
+						Application.Current.MainPage = flyoutPage;
+						ConnectToWindow();
+
+						_currentTest = () =>
+						{
+							flyoutPage.Flyout = CreateDestinationPage();
+							flyoutPage.Detail = new NavigationPage(CreateDestinationPage());
+							return Task.CompletedTask;
+						};
+					})
+				},
+
+				new Button()
+				{
+					Text = "Swap Tabbed Page",
+					AutomationId = "SwapTabbedPage",
+					Command = new Command( () =>
+					{
+						Application.Current.MainPage = new ContentPage() { Title = "Test", Content = new Label() {AutomationId = "BackgroundMe", Text = "Background/Minimize the app" } };
+						ConnectToWindow();
+						_currentTest = () =>
+						{
+							Application.Current.MainPage = new TabbedPage()
+							{
+								Children =
+								{
+									new NavigationPage(CreateDestinationPage())
+									{
+										Title = "Test"
+									},
+									new ContentPage() { Title = "Test", Content = new Label(){Text = "Second Page" } },
+								}
+							};
+							return Task.CompletedTask;
+						};
+					})
+				},
+				new Button()
+				{
+					Text = "Removing and Changing Tabs",
+					AutomationId = "RemoveAddTabs",
+					Command = new Command(() =>
+					{
+						var tabbedPage = new TabbedPage()
+						{
+							Children =
+							{
+								new ContentPage() { Title = "Test", Content = new Label() { AutomationId = "BackgroundMe", Text = "Background/Minimize the app" } },
+								new NavigationPage(CreateDestinationPage())
+								{
+									Title = "Test"
+								}
+							}
+						};
+
+						Application.Current.MainPage = tabbedPage;
+						ConnectToWindow();
+
+						_currentTest = () =>
+						{
+							tabbedPage.Children.RemoveAt(0);
+							tabbedPage.Children.Add(CreateDestinationPage());
+							return Task.CompletedTask;
+						};
+					})
+				},
+			};
+		}
+
+		ContentPage CreateDestinationPage()
+		{
+			return new ContentPage()
+			{
+				Title = "Test",
+				Content = new VerticalStackLayout()
+				{
+					new Button()
+					{
+						AutomationId = "Restore",
+						Text = "Restore",
+						Command = new Command(async ()=>
+						{
+							Application.Current.MainPage = _mainPage;
+
+							await Task.Yield();
+
+							foreach(var page in _modalStack)
+							{
+								await _mainPage.Navigation.PushModalAsync(page);
+							}
+						})
+					}
+				}
+			};
+		}
+	}
+}

src/Controls/src/Core/Platform/Android/Extensions/ToolbarExtensions.cs

@@ -84,10 +84,9 @@ public static void UpdateBackButton(this AToolbar nativeToolbar, Toolbar toolbar
 					nativeToolbar.Context ??
 					toolbar.Handler?.MauiContext?.Context;
 
-				nativeToolbar.NavigationIcon ??= new DrawerArrowDrawable(context!)
-				{
-					Progress = 1
-				};
+				nativeToolbar.NavigationIcon ??= new DrawerArrowDrawable(context!);
+				if (nativeToolbar.NavigationIcon is DrawerArrowDrawable iconDrawable)
+					iconDrawable.Progress = 1;
 
 				var backButtonTitle = toolbar.BackButtonTitle;
 				ImageSource image = toolbar.TitleIcon;
@@ -110,6 +109,9 @@ public static void UpdateBackButton(this AToolbar nativeToolbar, Toolbar toolbar
 				}
 				else
 				{
+					if (nativeToolbar.NavigationIcon is DrawerArrowDrawable iconDrawable)
+						iconDrawable.Progress = 0;
+
 					nativeToolbar.SetNavigationContentDescription(Resource.String.nav_app_bar_open_drawer_description);
 				}
 			}

src/Controls/src/Core/Platform/Android/TabbedPageManager.cs

@@ -3,15 +3,13 @@
 using System.Collections.Generic;
 using System.Collections.Specialized;
 using System.ComponentModel;
-using Android.App.Roles;
 using Android.Content;
 using Android.Content.Res;
 using Android.Graphics;
 using Android.Graphics.Drawables;
 using Android.Views;
 using AndroidX.CoordinatorLayout.Widget;
 using AndroidX.Fragment.App;
-using AndroidX.ViewPager.Widget;
 using AndroidX.ViewPager2.Widget;
 using Google.Android.Material.AppBar;
 using Google.Android.Material.BottomNavigation;
@@ -60,13 +58,11 @@ internal class TabbedPageManager
 		ColorStateList _currentBarTextColorStateList;
 		bool _tabItemStyleLoaded;
 		TabLayoutMediator _tabLayoutMediator;
-
-		NavigationRootManager NavigationRootManager { get; }
+		IDisposable _pendingFragment;
 
 		public TabbedPageManager(IMauiContext context)
 		{
 			_context = context;
-			NavigationRootManager = _context.GetNavigationRootManager();
 			_listeners = new Listeners(this);
 			_viewPager = new ViewPager2(context.Context)
 			{
@@ -175,6 +171,9 @@ void OnLayoutChanged(object sender, AView.LayoutChangeEventArgs e)
 
 		void RemoveTabs()
 		{
+			_pendingFragment?.Dispose();
+			_pendingFragment = null;
+
 			if (_tabLayoutFragment != null)
 			{
 				var fragment = _tabLayoutFragment;
@@ -189,13 +188,19 @@ void RemoveTabs()
 				{
 					SetContentBottomMargin(0);
 
-					_ = _context
-							.GetNavigationRootManager()
-							.FragmentManager
-							.BeginTransaction()
-							.Remove(fragment)
-							.SetReorderingAllowed(true)
-							.Commit();
+					if (_context?.Context is Context c)
+					{
+						_pendingFragment =
+							fragmentManager
+								.RunOrWaitForResume(c, fm =>
+								{
+									fm
+										.BeginTransaction()
+										.Remove(fragment)
+										.SetReorderingAllowed(true)
+										.Commit();
+								});
+					}
 				}
 
 				_tabplacementId = 0;
@@ -223,6 +228,9 @@ void RootViewChanged(object sender, EventArgs e)
 
 		internal void SetTabLayout()
 		{
+			_pendingFragment?.Dispose();
+			_pendingFragment = null;
+
 			int id;
 			var rootManager =
 				_context.GetNavigationRootManager();
@@ -231,7 +239,6 @@ internal void SetTabLayout()
 			if (rootManager.RootView == null)
 			{
 				rootManager.RootViewChanged += RootViewChanged;
-
 				return;
 			}
 
@@ -241,7 +248,6 @@ internal void SetTabLayout()
 				if (_tabplacementId == id)
 					return;
 
-				_tabLayoutFragment = new ViewFragment(BottomNavigationView);
 				SetContentBottomMargin(_context.Context.Resources.GetDimensionPixelSize(Resource.Dimension.design_bottom_navigation_height));
 			}
 			else
@@ -250,17 +256,34 @@ internal void SetTabLayout()
 				if (_tabplacementId == id)
 					return;
 
-				_tabLayoutFragment = new ViewFragment(TabLayout);
 				SetContentBottomMargin(0);
 			}
 
-			_tabplacementId = id;
-			_ = rootManager
-					.FragmentManager
-					.BeginTransaction()
-					.Replace(id, _tabLayoutFragment)
-					.SetReorderingAllowed(true)
-					.Commit();
+			if (_context?.Context is Context c)
+			{
+				_pendingFragment =
+					rootManager
+						.FragmentManager
+						.RunOrWaitForResume(c, fm =>
+						{
+							if (IsBottomTabPlacement)
+							{
+								_tabLayoutFragment = new ViewFragment(BottomNavigationView);
+							}
+							else
+							{
+								_tabLayoutFragment = new ViewFragment(TabLayout);
+							}
+
+							_tabplacementId = id;
+
+							fm
+								.BeginTransactionEx()
+								.ReplaceEx(id, _tabLayoutFragment)
+								.SetReorderingAllowed(true)
+								.Commit();
+						});
+			}
 		}
 
 		void SetContentBottomMargin(int bottomMargin)

src/Controls/tests/UITests/Tests/Issues/Issue11501.cs

@@ -0,0 +1,45 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.AppiumTests.Issues
+{
+	public class Issue11501 : _IssuesUITest
+	{
+		public Issue11501(TestDevice device) : base(device)
+		{
+		}
+
+		public override string Issue => "Making Fragment Changes While App is Backgrounded Fails";
+
+		[TestCase("SwapMainPage")]
+		[TestCase("SwapFlyoutPage")]
+		[TestCase("SwapTabbedPage")]
+		[TestCase("RemoveAddTabs")]
+		public async Task MakingFragmentRelatedChangesWhileAppIsBackgroundedFails(string scenario)
+		{
+			this.IgnoreIfPlatforms(new TestDevice[] { TestDevice.Mac, TestDevice.Windows });
+
+			try
+			{
+				App.WaitForElement(scenario);
+				App.Click(scenario);
+				App.BackgroundApp();
+
+				// Wait for app to finish backgrounding
+				await Task.Yield();
+				App.WaitForNoElement("BackgroundMe");
+				App.ForegroundApp();
+				App.WaitForElement("Restore");
+				App.Click("Restore");
+			}
+			catch
+			{
+				// Just in case these tests leave the app in an unreliable state
+				App.ResetApp();
+				FixtureSetup();
+				throw;
+			}
+		}
+	}
+}