[Windows] Fix select-all Entry select logic

src/Controls/src/Core/InputView/InputView.cs

@@ -274,6 +274,27 @@ string ITextInput.Text
 			set => SetValue(TextProperty, value, SetterSpecificity.FromHandler);
 		}
 
+		private protected override void OnBindablePropertySet(BindableProperty property, object original, object value, bool changed, bool willFirePropertyChanged)
+		{
+			base.OnBindablePropertySet(property, original, value, changed, willFirePropertyChanged);
+
+			// Note: these properties will always raise change events when set. On platforms like WinUI we 
+			// need to always push the xplat -> native value flow in scenarios such as "select all text on focus". If we 
+			// don't do this the native control will handle the input event and move the cursor after we set the selection
+			// length/cursor position, which is not the desired behavior.
+			if (!changed)
+			{
+				if (property.PropertyName == nameof(CursorPosition))
+				{
+					Handler?.UpdateValue(nameof(CursorPosition));
+				}
+				if (property.PropertyName == nameof(SelectionLength))
+				{
+					Handler?.UpdateValue(nameof(SelectionLength));
+				}
+		  }
+    }
+
 		private protected override string GetDebuggerDisplay()
 		{
 			return $"Text = {Text}, {base.GetDebuggerDisplay()}";

src/Controls/tests/TestCases.HostApp/Issues/EntrySelectionTest.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.Issues.EntrySelectionTest"
+             Title="EntrySelectionTest"
+             Background="White">
+  <VerticalStackLayout>
+    <Entry
+      x:Name="TextBox"
+      AutomationId="TextBox"
+      WidthRequest="300"
+      Focused="OnTextBoxFocused"/>
+    <Button
+      x:Name="OtherElement"
+      AutomationId="OtherElement"
+      Text="Other"
+      WidthRequest="128"/>
+  </VerticalStackLayout>
+</ContentPage>

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

@@ -0,0 +1,20 @@
+namespace Maui.Controls.Sample.Issues;
+
+[XamlCompilation(XamlCompilationOptions.Compile)]
+[Issue(IssueTracker.ManualTest, "EntrySelectionTest", "Entry select all text issue", PlatformAffected.UWP)]
+public partial class EntrySelectionTest : ContentPage
+{
+	public EntrySelectionTest()
+	{
+		InitializeComponent();
+	}
+
+	void OnTextBoxFocused(object sender, FocusEventArgs e)
+	{
+		if (TextBox.Text != null)
+		{
+			TextBox.CursorPosition = 0;
+			TextBox.SelectionLength = TextBox.Text.Length;
+		}
+	}
+}

src/Controls/tests/TestCases.WinUI.Tests/EntrySelectionTest.cs

@@ -0,0 +1,31 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests;
+
+public class EntrySelectionTest : _IssuesUITest
+{
+	public EntrySelectionTest(TestDevice device)
+		: base(device)
+	{ }
+
+	public override string Issue => "Entry select all text issue";
+
+	[Test]
+	[Category(UITestCategories.Entry)]
+	public void VerifySelectWorks()
+	{
+		App.WaitForElement("TextBox");
+		App.Click("TextBox");
+		App.EnterText("TextBox", "Hello World");
+
+		App.Click("OtherElement");
+		App.Click("TextBox");
+
+		App.Click("OtherElement");
+		App.Click("TextBox");
+
+		VerifyScreenshot();
+	}
+}

src/Core/src/Platform/Windows/TextBoxExtensions.cs

@@ -1,5 +1,6 @@
 #nullable enable
 using System;
+using System.Diagnostics;
 using Microsoft.Maui.Graphics;
 using Microsoft.UI.Xaml.Controls;
 using Microsoft.UI.Xaml.Input;
@@ -204,7 +205,10 @@ public static void UpdateVerticalTextAlignment(this TextBox textBox, ITextAlignm
 		public static void UpdateCursorPosition(this TextBox textBox, ITextInput entry)
 		{
 			// It seems that the TextBox does not limit the CursorPosition to the Text.Length natively
-			entry.CursorPosition = Math.Min(entry.CursorPosition, textBox.Text.Length);
+			var clampedPos = Math.Min(entry.CursorPosition, textBox.Text.Length);
+
+			if (entry.CursorPosition != clampedPos)
+				entry.CursorPosition = clampedPos;
 
 			if (textBox.SelectionStart != entry.CursorPosition)
 				textBox.SelectionStart = entry.CursorPosition;
@@ -213,7 +217,10 @@ public static void UpdateCursorPosition(this TextBox textBox, ITextInput entry)
 		public static void UpdateSelectionLength(this TextBox textBox, ITextInput entry)
 		{
 			// It seems that the TextBox does not limit the SelectionLength to the Text.Length natively
-			entry.SelectionLength = Math.Min(entry.SelectionLength, textBox.Text.Length - textBox.SelectionStart);
+			var clampedLen = Math.Min(entry.SelectionLength, textBox.Text.Length - textBox.SelectionStart);
+
+			if (entry.SelectionLength != clampedLen)
+				entry.SelectionLength = clampedLen;
 
 			if (textBox.SelectionLength != entry.SelectionLength)
 				textBox.SelectionLength = entry.SelectionLength;