Fix Shell Flyout Menu Visibility Issue When Navigating Between TabBar…

… and Flyout Items (dotnet#25510)

* 25436 - Flyout menu should be visible after navigating from a menu item

* Alternative fix committed

* Added the testcases and its images

* Committed the windows image and changed the tap coordinates to Xpath for Android

---------

Co-authored-by: Karthik Raja <92788387+karthikraja-arumugam@users.noreply.github.com>
Co-authored-by: AhamedAliNishad <ahamedalinishad.j@syncfusion.com>
Co-authored-by: Rui Marinho <me@ruimarinho.net>

src/Controls/src/Core/Shell/Shell.cs

@@ -1860,7 +1860,7 @@ ShellAppearance GetAppearanceForPivot(Element pivot)
 			return null;
 		}
 
-		void NotifyFlyoutBehaviorObservers()
+		internal void NotifyFlyoutBehaviorObservers()
 		{
 			if (CurrentItem == null || GetVisiblePage() == null)
 				return;

src/Controls/src/Core/Shell/ShellContent.cs

@@ -229,11 +229,14 @@ internal void EvaluateDisconnect()
 			// If the user has set the IsVisible property on this shell content to false
 			bool disconnect = true;
 
-			if (Parent is ShellSection shellSection &&
+			Shell shell = null;
+
+      if (Parent is ShellSection shellSection &&
 				shellSection.Parent is ShellItem shellItem &&
-				shellItem.Parent is Shell shell)
+				shellItem.Parent is Shell shellInstance)
 			{
-				disconnect =
+				shell = shellInstance;
+				disconnect = 
 					!this.IsVisible || // user has set the IsVisible property to false
 					(_contentCache is not null && !_contentCache.IsVisible) || // user has set IsVisible on the Page to false
 					shell.CurrentItem != shellItem || // user has navigated to a different TabBar or a different FlyoutItem
@@ -243,6 +246,7 @@ shellSection.Parent is ShellItem shellItem &&
 
 			if (!disconnect)
 			{
+				shell?.NotifyFlyoutBehaviorObservers();
 				return;
 			}
 

src/Controls/tests/TestCases.HostApp/Issues/Issue25436.xaml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<local:TestShell xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             xmlns:local="using:Maui.Controls.Sample.Issues"
+             xmlns:issues="clr-namespace:Maui.Controls.Sample.Issues"
+              x:Class="Maui.Controls.Sample.Issues.Issue25436">
+
+<FlyoutItem  Title="Home" >
+    <ShellContent
+        ContentTemplate="{DataTemplate issues:Issue25436Firstpage}"
+        Route="home" />
+  </FlyoutItem>
+  <TabBar>
+    <ShellContent
+        ContentTemplate="{DataTemplate issues:Issue25436LoginPage}"
+        Route="login" />
+  </TabBar>
+
+</local:TestShell>

src/Controls/tests/TestCases.HostApp/Issues/Issue25436.xaml.cs

@@ -0,0 +1,98 @@
+using Maui.Controls.Sample.Issues;
+
+namespace Maui.Controls.Sample.Issues
+{
+	[Issue(IssueTracker.Github, 25436, "[.NET 9] Shell Flyout menu not rendering after navigating from a MenuItem page", PlatformAffected.All)]
+	public partial class Issue25436 : TestShell
+	{
+		public Issue25436()
+		{
+			InitializeComponent();
+		}
+		protected override void Init()
+		{
+
+		}
+
+	}
+	public class Issue25436Firstpage : ContentPage
+	{
+		public Issue25436Firstpage()
+		{
+			var button = new Button
+			{
+				Text = "Click here to navigate back",
+				VerticalOptions = LayoutOptions.Center,
+				HorizontalOptions = LayoutOptions.Center
+			};
+			button.Clicked += async (s, e) => await Shell.Current.GoToAsync("//login");
+			Content = button;
+			button.AutomationId = "BackButton";
+			Title = "_25436 first flyout";
+		}
+	}
+
+	public class Issue25436LoginPage : ContentPage
+	{
+		Issue25436INavigationService _navigationService;
+		public Issue25436LoginPage(Issue25436INavigationService navigationService)
+		{
+			_navigationService = navigationService;
+			var loginButton = new Button
+			{
+				Text = "Login"
+			};
+			loginButton.AutomationId = "Login";
+			loginButton.Clicked += OnLoginButtonClicked;
+
+			Content = new StackLayout
+			{
+				Children =
+			{
+				new Label { Text = "This is the login page" },
+				loginButton
+			}
+			};
+			Title = "_25436 login page";
+		}
+		private async void OnLoginButtonClicked(object sender, EventArgs e)
+		{
+			await _navigationService.GoToAsync("//home");
+		}
+	}
+
+	static class Issue25436Extensions
+	{
+		public static MauiAppBuilder Issue25436RegisterNavigationService(this MauiAppBuilder builder)
+		{
+			// Register services
+			builder.Services.AddSingleton<Issue25436INavigationService, Issue25436NavigationService>();
+
+			// Register pages
+			builder.Services.AddTransient<Issue25436LoginPage>();
+			builder.Services.AddSingleton<Issue25436Firstpage>();
+
+			return builder;
+		}
+	}
+
+	public interface Issue25436INavigationService
+	{
+		Task GoToAsync(string route);
+	}
+
+	public partial class Issue25436NavigationService : Issue25436INavigationService
+	{
+		public Task GoToAsync(string route)
+		{
+			if (Shell.Current is null)
+			{
+				throw new NotSupportedException($"Navigation with the '{nameof(GoToAsync)}' method is currently supported only with a Shell-enabled application.");
+			}
+
+			return Shell.Current.GoToAsync(route);
+		}
+	}
+
+}
+

src/Controls/tests/TestCases.HostApp/MauiProgram.cs

@@ -26,7 +26,8 @@ public static MauiApp CreateMauiApp()
 				.Issue18720AddMappers()
 				.Issue18720EditorAddMappers()
 				.Issue18720DatePickerAddMappers()
-				.Issue18720TimePickerAddMappers();
+				.Issue18720TimePickerAddMappers()
+				.Issue25436RegisterNavigationService();
 
 #if IOS || MACCATALYST
 

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue25436.cs

@@ -0,0 +1,32 @@
+#if !MACCATALYST
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues
+{
+    internal class Issue25436 : _IssuesUITest
+	{
+		public override string Issue => "[.NET 9] Shell Flyout menu not rendering after navigating from a MenuItem page";
+
+		public Issue25436(TestDevice testDevice) : base(testDevice) { }
+
+		[Test]
+		[Category(UITestCategories.Shell)]
+		public void FlyoutMenuShouldNotDisappearWhenNavigateUsingServices()
+		{
+			App.WaitForElement("BackButton");
+			App.Tap("BackButton");
+			App.WaitForElement("Login");
+			App.Tap("Login");
+#if ANDROID
+			App.Tap(AppiumQuery.ByXPath("//android.widget.ImageButton[@content-desc='Open navigation drawer']"));
+#else
+			App.Tap(FlyoutIconAutomationId);
+#endif
+			VerifyScreenshot();
+		}
+
+	}
+}
+#endif