[Android] Fix for Search Handler visual and functional bug in subtabs

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

@@ -35,6 +35,7 @@ namespace Microsoft.Maui.Controls.Platform.Compatibility
 {
 	public class ShellToolbarTracker : Java.Lang.Object, AView.IOnClickListener, IShellToolbarTracker, IFlyoutBehaviorObserver
 	{
+		const int _placeholderMenuItemId = 100;
 		#region IFlyoutBehaviorObserver
 
 		void IFlyoutBehaviorObserver.OnFlyoutBehaviorChanged(FlyoutBehavior behavior)
@@ -632,7 +633,6 @@ protected virtual void UpdateTitleView(Context context, AToolbar toolbar, View t
 		private void UpdateToolbarItemsTintColors(AToolbar toolbar)
 		{
 			var menu = toolbar.Menu;
-			int _placeholderMenuItemId = 100;
 			if (menu.FindItem(_placeholderMenuItemId) is IMenuItem item)
 			{
 				using (var icon = item.Icon)
@@ -643,7 +643,6 @@ private void UpdateToolbarItemsTintColors(AToolbar toolbar)
 		protected virtual void UpdateToolbarItems(AToolbar toolbar, Page page)
 		{
 			var menu = toolbar.Menu;
-			int _placeholderMenuItemId = 100;
 			SearchHandler = Shell.GetSearchHandler(page);
 			if (SearchHandler != null && SearchHandler.SearchBoxVisibility != SearchBoxVisibility.Hidden)
 			{
@@ -662,6 +661,8 @@ protected virtual void UpdateToolbarItems(AToolbar toolbar, Page page)
 
 				if (SearchHandler.SearchBoxVisibility == SearchBoxVisibility.Collapsible)
 				{
+					menu.RemoveItem(_placeholderMenuItemId);
+
 					var placeholder = new Java.Lang.String(SearchHandler.Placeholder);
 					var item = menu.Add(0, _placeholderMenuItemId, 0, placeholder);
 					placeholder.Dispose();

src/Controls/tests/TestCases.HostApp/Issues/Issue21119.cs

@@ -0,0 +1,108 @@
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 21119, "Search Handler visual and functional bug in subtabs", PlatformAffected.Android)]
+public class Issue21119 : Shell
+{
+	public Issue21119()
+	{
+		FlyoutBehavior = FlyoutBehavior.Flyout;
+
+		var flyoutItem = new FlyoutItem
+		{
+			Route = "animals",
+			FlyoutDisplayOptions = FlyoutDisplayOptions.AsMultipleItems
+		};
+
+		var domesticTab = new Tab
+		{
+			Title = "Domestic",
+			Route = "domestic"
+		};
+
+		domesticTab.Items.Add(new ShellContent
+		{
+			Title = "CatsPage",
+			Route = "cats",
+			ContentTemplate = new DataTemplate(typeof(_21119CatsPage))
+		});
+
+		domesticTab.Items.Add(new ShellContent
+		{
+			Title = "DogsPage",
+			Route = "dogs",
+			ContentTemplate = new DataTemplate(typeof(_21119DogsPage))
+		});
+
+		flyoutItem.Items.Add(domesticTab);
+
+		Items.Add(flyoutItem);
+	}
+
+	public class _21119CatsPage : ContentPage
+	{
+		public _21119CatsPage()
+		{
+			Title = "CatsPage";
+
+			var searchHandler = new _21119AnimalSearchHandler
+			{
+				Placeholder = "Search cats...",
+				ShowsResults = true
+			};
+
+			var catPageButton = new Button
+			{
+				Text = "CatPageButton",
+				AutomationId = "CatPageButton"
+			};
+
+			Content = new StackLayout
+			{
+				Children =
+				{
+					catPageButton
+				}
+			};
+
+			Shell.SetSearchHandler(this, searchHandler);
+		}
+	}
+
+	public class _21119DogsPage : ContentPage
+	{
+		public _21119DogsPage()
+		{
+			Title = "DogsPage";
+
+			var searchHandler = new _21119AnimalSearchHandler
+			{
+				Placeholder = "Search dogs...",
+				ShowsResults = true
+			};
+
+			Shell.SetSearchHandler(this, searchHandler);
+
+			var dogPageButton = new Button
+			{
+				Text = "DogPageButton",
+				AutomationId = "DogsPageButton"
+			};
+
+			Content = new StackLayout
+			{
+				Children =
+				{
+					dogPageButton
+				}
+			};
+		}
+	}
+
+	public class _21119AnimalSearchHandler : SearchHandler
+	{
+		public _21119AnimalSearchHandler()
+		{
+			SearchBoxVisibility = SearchBoxVisibility.Collapsible;
+		}
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue21119.cs

@@ -0,0 +1,35 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues
+{
+	public class Issue21119 : _IssuesUITest
+	{
+		public Issue21119(TestDevice testDevice) : base(testDevice)
+		{
+		}
+
+		public override string Issue => "Search Handler visual and functional bug in subtabs";
+
+		[Test]
+		[Category(UITestCategories.Shell)]
+		public void UpdateSearchHandlerMenuItemForTabNavigation()
+		{
+#if WINDOWS
+			App.Tap("navViewItem");
+			App.WaitForElement("DogsPage");
+			App.Tap("DogsPage");
+			App.Tap("navViewItem");
+			App.WaitForElement("CatsPage");
+			App.Tap("CatsPage");
+#else
+			App.WaitForElement("CatPageButton");
+			App.TapTab("DogsPage");
+			App.WaitForElement("DogPageButton");
+			App.TapTab("CatsPage");
+#endif
+			VerifyScreenshot();
+		}
+	}
+}