Fixed Editor vertical text alignment not working after toggling IsVisible

src/Controls/tests/TestCases.HostApp/Issues/Issue25973.xaml

@@ -0,0 +1,22 @@
+<?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.Issues.Issue25973">
+
+        <ScrollView>
+            <VerticalStackLayout>
+                <Editor
+                    x:Name="editor"
+                    AutomationId="Editor"
+                    Text="Editor Text in Vertical End"
+                    IsVisible="False"
+                    VerticalTextAlignment="End"
+                    HeightRequest="100"/>
+                <Button
+                    x:Name="toggleButton"
+                    AutomationId="ToggleButton"
+                    Text="Change Visibility"
+                    Clicked="VisibilityButtonClicked"/>
+            </VerticalStackLayout>
+        </ScrollView>
+</ContentPage>

src/Controls/tests/TestCases.HostApp/Issues/Issue25973.xaml.cs

@@ -0,0 +1,16 @@
+namespace Maui.Controls.Sample.Issues
+{
+	[Issue(IssueTracker.Github, 25973, "Editor vertical text alignment not working after toggling IsVisible", PlatformAffected.UWP)]
+	public partial class Issue25973 : ContentPage
+	{
+		public Issue25973()
+		{
+			InitializeComponent();
+		}
+
+		private void VisibilityButtonClicked(object sender, EventArgs e)
+		{
+			editor.IsVisible = true;
+		}
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue25973.cs

@@ -0,0 +1,25 @@
+using NUnit.Framework;
+using NUnit.Framework.Legacy;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues
+{
+	internal class Issue25973 : _IssuesUITest
+	{
+		public override string Issue => "Editor vertical text alignment not working after toggling IsVisible";
+
+		public Issue25973(TestDevice device) : base(device)
+		{
+		}
+
+		[Test]
+		[Category(UITestCategories.Editor)]
+		public void VerifyEditorVerticalTextAlignmentWhenVisibilityToggled()
+		{
+			App.WaitForElement("ToggleButton");
+			App.Click("ToggleButton");
+			VerifyScreenshot();
+		}
+	}
+}

src/Core/src/Handlers/Editor/EditorHandler.Windows.cs

@@ -30,12 +30,12 @@ protected override void ConnectHandler(TextBox platformView)
 		{
 			platformView.TextChanged += OnTextChanged;
 			platformView.LostFocus += OnLostFocus;
-			platformView.Loaded += OnPlatformLoaded;
+			platformView.SizeChanged += OnPlatformViewSizeChanged;
 		}
 
 		protected override void DisconnectHandler(TextBox platformView)
 		{
-			platformView.Loaded -= OnPlatformLoaded;
+			platformView.SizeChanged -= OnPlatformViewSizeChanged;
 			platformView.TextChanged -= OnTextChanged;
 			platformView.LostFocus -= OnLostFocus;
 
@@ -99,7 +99,7 @@ void OnTextChanged(object sender, TextChangedEventArgs args) =>
 		void OnLostFocus(object? sender, RoutedEventArgs e) =>
 			VirtualView?.Completed();
 
-		void OnPlatformLoaded(object sender, RoutedEventArgs e) =>
+		void OnPlatformViewSizeChanged(object sender, SizeChangedEventArgs e) =>
 			MauiTextBox.InvalidateAttachedProperties(PlatformView);
 
 		private void OnSelectionChanged(object sender, RoutedEventArgs e)