Add SelectTextOnFocusBehavior to automatically select the content of a TextBox when it is focused.

.config/dotnet-tools.json

@@ -15,7 +15,7 @@
       ]
     },
     "microsoft.visualstudio.slngen.tool": {
-      "version": "12.0.13",
+      "version": "12.0.32",
       "commands": [
         "slngen"
       ]

components/Behaviors/samples/Behaviors.Samples.csproj

@@ -1,4 +1,4 @@
-<Project>
+<Project>
   <Import Project="$([MSBuild]::GetPathOfFileAbove(Directory.Build.props))" Condition="Exists('$([MSBuild]::GetPathOfFileAbove(Directory.Build.props))')" />
 
   <PropertyGroup>

components/Behaviors/samples/Behaviors.md

@@ -28,6 +28,12 @@ The AutoSelectBehavior automatically selects the entire content of its associate
 
 > [!Sample AutoSelectBehaviorSample]
 
+## SelectTextOnFocusBehavior
+
+The SelectTextOnFocusBehavior automatically selects the entire content of its associated TextBox when it receives focus.
+
+> [!Sample SelectTextOnFocusBehaviorSample]
+
 ## ViewportBehavior
 
 This behavior allows you to listen an element enter or exit the ScrollViewer viewport.

components/Behaviors/samples/SelectTextOnFocusBehaviorSample.xaml

@@ -0,0 +1,17 @@
+<Page x:Class="BehaviorsExperiment.Samples.SelectTextOnFocusBehaviorSample"
+      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+      xmlns:behaviors="using:CommunityToolkit.WinUI.Behaviors"
+      xmlns:interactivity="using:Microsoft.Xaml.Interactivity">
+
+    <StackPanel MaxWidth="480"
+                Spacing="8">
+        <TextBox Text="My content is not selected when focused" />
+        <TextBox Text="My content is selected when focused">
+            <interactivity:Interaction.Behaviors>
+                <behaviors:SelectTextOnFocusBehavior />
+            </interactivity:Interaction.Behaviors>
+        </TextBox>
+    </StackPanel>
+</Page>
+

components/Behaviors/samples/SelectTextOnFocusBehaviorSample.xaml.cs

@@ -0,0 +1,16 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using CommunityToolkit.WinUI.Behaviors;
+
+namespace BehaviorsExperiment.Samples;
+
+[ToolkitSample(id: nameof(SelectTextOnFocusBehaviorSample), nameof(SelectTextOnFocusBehavior), description: $"A sample for showing how to use the SelectTextOnFocusBehavior.")]
+public sealed partial class SelectTextOnFocusBehaviorSample : Page
+{
+    public SelectTextOnFocusBehaviorSample()
+    {
+        this.InitializeComponent();
+    }
+}

components/Behaviors/src/ReadMe.md

@@ -16,6 +16,7 @@ This package contains the following in the `CommunityToolkit.WinUI.Behaviors` na
 - KeyDownTriggerBehavior
 - NavigateToUriAction
 - QuickReturnHeaderBehavior
+- SelectTextOnFocusBehavior
 - StartAnimationAction
 - StackedNotificationBehavior
 - StopAnimationAction

components/Behaviors/src/Select/SelectTextOnFocusBehavior.cs

@@ -0,0 +1,27 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace CommunityToolkit.WinUI.Behaviors;
+
+/// <summary>
+/// This behavior automatically selects the text of the associated <see cref="TextBox"/> when it receives the focus.
+/// </summary>
+public sealed class SelectTextOnFocusBehavior : BehaviorBase<TextBox>
+{
+    /// <inheritdoc/>
+    protected override bool Initialize()
+    {
+        AssociatedObject.GotFocus += OnAssociatedObjectGotFocus;
+        return base.Initialize();
+    }
+
+    /// <inheritdoc/>
+    protected override bool Uninitialize()
+    {
+        AssociatedObject.GotFocus -= OnAssociatedObjectGotFocus;
+        return base.Uninitialize();
+    }
+
+    private void OnAssociatedObjectGotFocus(object sender, RoutedEventArgs e) => AssociatedObject.SelectAll();
+}