Fix memory leak in FlyoutPage when changing the Detail

src/Controls/samples/Controls.Sample.Sandbox/App.xaml.cs

@@ -9,16 +9,6 @@ public App()
 
 	protected override Window CreateWindow(IActivationState? activationState)
 	{
-		// To test shell scenarios, change this to true
-		bool useShell = false;
-
-		if (!useShell)
-		{
-			return new Window(new NavigationPage(new MainPage()));
-		}
-		else
-		{
-			return new Window(new SandboxShell());
-		}
+		return new Window(new AppFlyoutPage());
 	}
 }

src/Controls/samples/Controls.Sample.Sandbox/AppFlyoutPage.xaml

@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<FlyoutPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+            xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+            x:Class="Maui.Controls.Sample.AppFlyoutPage"
+            Title="AppFlyoutPage">
+    <FlyoutPage.Flyout>
+        <ContentPage Title="Menu">
+            <CollectionView ItemsSource="{Binding MenuItems}"
+                            SelectionMode="Single"
+                            SelectionChanged="OnMenuItemSelected">
+                <CollectionView.ItemTemplate>
+                    <DataTemplate>
+                        <Grid Padding="10">
+                            <Label Text="{Binding Title}" 
+                                   FontSize="16"
+                                   VerticalOptions="Center"/>
+                        </Grid>
+                    </DataTemplate>
+                </CollectionView.ItemTemplate>
+            </CollectionView>
+        </ContentPage>
+    </FlyoutPage.Flyout>
+</FlyoutPage>

src/Controls/samples/Controls.Sample.Sandbox/AppFlyoutPage.xaml.cs

@@ -0,0 +1,42 @@
+using Maui.Controls.Sample.Services;
+
+namespace Maui.Controls.Sample;
+
+public partial class AppFlyoutPage : FlyoutPage
+{
+	public class MenuItem
+	{
+		public string Title { get; set; } = string.Empty;
+		public Type PageType { get; set; } = typeof(Page);
+	}
+
+	public List<MenuItem> MenuItems { get; set; }
+
+	public AppFlyoutPage()
+	{
+		InitializeComponent();
+
+		MenuItems = new List<MenuItem>
+		{
+			new MenuItem { Title = "page 1", PageType = typeof(Page1) },
+			new MenuItem { Title = "page 2", PageType = typeof(Page2) }
+		};
+
+		BindingContext = this;
+
+		// Set default detail page
+		Detail = new NavigationPage(new Page1());
+	}
+
+	private void OnMenuItemSelected(object? sender, SelectionChangedEventArgs e)
+	{
+		if (e.CurrentSelection.FirstOrDefault() is MenuItem selectedItem)
+		{
+			var navigationService = new NavigationService();
+			navigationService.Navigate(selectedItem.PageType);
+
+			// Close the flyout after selection
+			IsPresented = false;
+		}
+	}
+}

src/Controls/samples/Controls.Sample.Sandbox/Page1.xaml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             x:Class="Maui.Controls.Sample.Page1"
+             Title="page 1">
+    <VerticalStackLayout Padding="30"
+                         Spacing="25"
+                         VerticalOptions="Center"
+                         HorizontalOptions="Center">
+        <Button Text="page 1"
+                Clicked="OnNavigateToPage2Clicked"
+                HorizontalOptions="Center"/>
+        <Button Text="Navigate to Page 2"
+                Clicked="OnNavigateToPage2AsyncClicked"
+                HorizontalOptions="Center"/>
+
+        <Entry Text="Test"/>
+    </VerticalStackLayout>
+</ContentPage>

src/Controls/samples/Controls.Sample.Sandbox/Page1.xaml.cs

@@ -0,0 +1,29 @@
+using Maui.Controls.Sample.Services;
+
+namespace Maui.Controls.Sample;
+
+public partial class Page1 : ContentPage
+{
+	private readonly NavigationService _navigationService;
+
+	public Page1()
+	{
+		InitializeComponent();
+		_navigationService = new NavigationService();
+
+		Loaded += (e, __) =>
+		{
+			_ = MemoryTest.IsAliveAsync();
+		};
+	}
+
+	private void OnNavigateToPage2Clicked(object? sender, EventArgs e)
+	{
+		_navigationService.NavigateAbsolute(typeof(Page2));
+	}
+
+	private void OnNavigateToPage2AsyncClicked(object? sender, EventArgs e)
+	{
+		 _navigationService.Navigate(typeof(Page2));
+	}
+}

src/Controls/samples/Controls.Sample.Sandbox/Page2.xaml

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             x:Class="Maui.Controls.Sample.Page2"
+             Title="page 2">
+    <VerticalStackLayout Padding="30"
+                         Spacing="25"
+                         VerticalOptions="Center"
+                         HorizontalOptions="Center">
+        <Label Text="page 2"
+               FontSize="32"
+               HorizontalOptions="Center"/>
+        <Button Text="Navigate to Page 1"
+                Clicked="OnNavigateToPage1Clicked"
+                HorizontalOptions="Center"/>
+        <Entry Text="Test"/>
+    </VerticalStackLayout>
+</ContentPage>

src/Controls/samples/Controls.Sample.Sandbox/Page2.xaml.cs

@@ -0,0 +1,19 @@
+using Maui.Controls.Sample.Services;
+
+namespace Maui.Controls.Sample;
+
+public partial class Page2 : ContentPage
+{
+	private readonly NavigationService _navigationService;
+
+	public Page2()
+	{
+		InitializeComponent();
+		_navigationService = new NavigationService();
+	}
+
+	private void OnNavigateToPage1Clicked(object? sender, EventArgs e)
+	{
+		 _navigationService.Navigate(typeof(Page1));
+	}
+}

src/Controls/samples/Controls.Sample.Sandbox/Services/NavigationService.cs

@@ -0,0 +1,102 @@
+namespace Maui.Controls.Sample.Services;
+
+public class NavigationService
+{
+	public void NavigateAbsolute(Type pageType)
+	{
+		var flyoutPage = new AppFlyoutPage();
+
+		if (pageType == typeof(Page1))
+		{
+			flyoutPage.Detail = new NavigationPage(new Page1());
+		}
+		else if (pageType == typeof(Page2))
+		{
+			flyoutPage.Detail = new NavigationPage(new Page2());
+		}
+
+		var page = (flyoutPage.Detail as NavigationPage)!.CurrentPage;
+
+		MemoryTest.Add(flyoutPage);
+		MemoryTest.Add(flyoutPage.Detail);
+		MemoryTest.Add(page);
+		Application.Current!.Windows[0].Page = flyoutPage;
+	}
+
+	public void  Navigate(Type pageType)
+	{
+		var currentPage = Application.Current!.Windows[0].Page;
+
+		if (currentPage is FlyoutPage flyoutPage && flyoutPage.Detail is NavigationPage navigationPage)
+		{
+			Page? targetPage = null;
+
+			if (pageType == typeof(Page1))
+			{
+				targetPage = new Page1();
+			}
+			else if (pageType == typeof(Page2))
+			{
+				targetPage = new Page2();
+			}
+
+			if (targetPage != null)
+			{
+				flyoutPage.Detail = new NavigationPage(targetPage);
+				flyoutPage.IsPresented = false;
+			}
+
+
+			MemoryTest.Add(flyoutPage);
+			MemoryTest.Add(flyoutPage.Detail);
+			MemoryTest.Add(targetPage!);
+		}
+	}
+}
+static class MemoryTest
+{
+	static readonly List<WeakReference<object>> weakReferences = [];
+
+	public static int Count => weakReferences.Count;
+
+	public static void Add(object obj)
+	{
+		weakReferences.Add(new(obj));
+	}
+
+	public static async Task IsAliveAsync()
+	{
+		RunGC();
+		for (var i = 0; i < weakReferences.Count; i++)
+		{
+			var item = weakReferences[i];
+
+			if (item.TryGetTarget(out var target))
+			{
+				var type = target.GetType();
+				var name = type.FullName;
+
+#pragma warning disable CS0618 // Type or member is obsolete
+				await App.Current!.MainPage!.DisplayAlert("Memory leak!", $"The {name} object of {type} Type is still alive", "Ok");
+#pragma warning restore CS0618 // Type or member is obsolete
+			}
+			else
+			{
+				weakReferences.Remove(item);
+			}
+			RunGC();
+		}
+
+
+#pragma warning disable CS0618 // Type or member is obsolete
+				await App.Current!.MainPage!.DisplayAlert("Memory leak!", $"The are {weakReferences.Count} objects still alive", "Ok");
+#pragma warning restore CS0618 // Type or member is obsolete
+	}
+
+	static void RunGC()
+	{
+		GC.Collect();
+		GC.WaitForPendingFinalizers();
+		GC.Collect();
+	}
+}

src/Controls/src/Core/FlyoutPage/FlyoutPage.cs

@@ -76,6 +76,7 @@ public Page Detail
 				{
 					previousDetail.SendNavigatedFrom(
 						new NavigatedFromEventArgs(destinationPage: value, NavigationType.Replace));
+					previousDetail.Handler?.DisconnectHandler();
 				}
 
 				_detail.SendNavigatedTo(new NavigatedToEventArgs(previousDetail, NavigationType.Replace));

src/Controls/tests/DeviceTests/Memory/MemoryTests.cs

@@ -85,6 +85,7 @@ void SetupBuilder()
 				handlers.AddHandler<TimePicker, TimePickerHandler>();
 				handlers.AddHandler<Toolbar, ToolbarHandler>();
 				handlers.AddHandler<WebView, WebViewHandler>();
+				handlers.AddHandler<FlyoutPage, FlyoutViewHandler>();
 
 #if IOS || MACCATALYST
 				handlers.AddHandler<NavigationPage, NavigationRenderer>();
@@ -577,6 +578,91 @@ await CreateHandlerAndAddToWindow(window, async () =>
 		await AssertionExtensions.WaitForGC([.. references]);
 	}
 
+	[Fact("FlyoutPage Detail Handler Is Disconnected When Replaced")]
+	public async Task FlyoutPageDetailDoesNotLeak()
+	{
+		SetupBuilder();
+
+		var references = new List<WeakReference>();
+		var flyoutPage = new FlyoutPage
+		{
+			Flyout = new ContentPage { Title = "Flyout" },
+			Detail = new NavigationPage(new ContentPage { Title = "Initial Detail" })
+		};
+
+		await CreateHandlerAndAddToWindow(new Window(flyoutPage), async () =>
+		{
+			await OnLoadedAsync(flyoutPage);
+
+			// Capture old detail and its handler before replacement
+			var oldDetail = flyoutPage.Detail;
+			var oldHandler = oldDetail.Handler;
+			Assert.NotNull(oldHandler);
+
+			references.Add(new(oldDetail));
+			references.Add(new(oldHandler));
+			references.Add(new(oldHandler.PlatformView));
+
+			// Replace detail
+			var newDetailPage = new ContentPage { Title = "New Detail" };
+			flyoutPage.Detail = new NavigationPage(newDetailPage);
+			await OnLoadedAsync(newDetailPage);
+
+			// The fix calls previousDetail.Handler?.DisconnectHandler() in the Detail setter.
+			// Without the fix, the old handler stays connected (non-null).
+			Assert.Null(oldDetail.Handler);
+
+			oldDetail = null;
+			oldHandler = null;
+		});
+
+		await AssertionExtensions.WaitForGC([.. references]);
+	}
+
+	[Fact("FlyoutPage Detail Handler Disconnects With Multiple Replacements")]
+	public async Task FlyoutPageDetailDoesNotLeakWithMultipleReplacements()
+	{
+		SetupBuilder();
+
+		var references = new List<WeakReference>();
+		var flyoutPage = new FlyoutPage
+		{
+			Flyout = new ContentPage { Title = "Flyout" },
+			Detail = new NavigationPage(new ContentPage { Title = "Initial Detail" })
+		};
+
+		await CreateHandlerAndAddToWindow(new Window(flyoutPage), async () =>
+		{
+			await OnLoadedAsync(flyoutPage);
+
+			for (int i = 0; i < 5; i++)
+			{
+				var oldDetail = flyoutPage.Detail;
+				var oldHandler = oldDetail.Handler;
+				Assert.NotNull(oldHandler);
+
+				if (i < 3)
+				{
+					references.Add(new(oldDetail));
+					references.Add(new(oldHandler));
+					references.Add(new(oldHandler.PlatformView));
+				}
+
+				var newDetailPage = new ContentPage { Title = $"Detail {i}" };
+				flyoutPage.Detail = new NavigationPage(newDetailPage);
+				await OnLoadedAsync(newDetailPage);
+
+				// Each replacement must disconnect the previous detail's handler
+				Assert.Null(oldDetail.Handler);
+
+				oldDetail = null;
+				oldHandler = null;
+			}
+		});
+
+		await AssertionExtensions.WaitForGC([.. references]);
+	}
+
 	[Fact("VisualDiagnosticsOverlay Does Not Leak"
 #if IOS || MACCATALYST
 		, Skip = "Fails with 'MauiContext should have been set on parent.'"

src/Core/src/Platform/Android/Navigation/MauiNavHostFragment.cs

@@ -18,5 +18,11 @@ public MauiNavHostFragment()
 		protected MauiNavHostFragment(nint javaReference, JniHandleOwnership transfer) : base(javaReference, transfer)
 		{
 		}
+
+		public override void OnDestroy()
+		{
+			base.OnDestroy();
+			this.Dispose();
+		}
 	}
 }