How to automatically select all text on focus in WPF TextBox

Question

If I call SelectAll from a GotFocus event handler  it doesn t work with the mouse - the selection disappears as soon as mouse is released   EDIT  People are liking Donnelle s answer  I ll try to explain why I did not like it as much as the accepted answer    It is more complex  while the accepted answer does the same thing in a simpler way  The usability of accepted answer is better  When you click in the middle of the text  text gets unselected when you release the mouse allowing you to start editing instantly  and if you still want to select all  just press the button again and this time it will not unselect on release  Following Donelle s recipe  if I click in the middle of text  I have to click second time to be able to edit  If I click somewhere within the text versus outside of the text  this most probably means I want to start editing instead of overwriting everything

User · Answer

I have a slightly simplified answer for this (with just the PreviewMouseLeftButtonDown event) which seems to mimic the usual functionality of a browser:

In XAML you have a TextBox say:

<TextBox Text="http://www.blabla.com" BorderThickness="2" BorderBrush="Green" VerticalAlignment="Center" Height="25"
                 PreviewMouseLeftButtonDown="SelectAll" />

In codebehind:

private void SelectAll(object sender, MouseButtonEventArgs e)
{
    TextBox tb = (sender as TextBox);

    if (tb == null)
    {
        return;
    }

    if (!tb.IsKeyboardFocusWithin)
    {
        tb.SelectAll();
        e.Handled = true;
        tb.Focus();
    }
}

User · Answer

I have tested all of them but only the following worked out   protected override void OnStartup StartupEventArgs e         EventManager RegisterClassHandler typeof TextBox   UIElement PreviewMouseLeftButtonDownEvent     new MouseButtonEventHandler SelectivelyHandleMouseButton   true       EventManager RegisterClassHandler typeof TextBox   UIElement GotKeyboardFocusEvent        new RoutedEventHandler SelectAllText   true       EventManager RegisterClassHandler typeof TextBox   UIElement GotFocusEvent        new RoutedEventHandler GotFocus   true                private static void SelectivelyHandleMouseButton object sender  MouseButtonEventArgs e        var textbox    sender as TextBox       if  textbox    null                int hc   textbox GetHashCode            if  hc    LastHashCode                        if  e OriginalSource GetType   Name     TextBoxView                                 e Handled   true                  textbox Focus                    LastHashCode   -1                                    if  textbox    null  textbox Focus       private static void SelectAllText object sender  RoutedEventArgs e        var textBox   e OriginalSource as TextBox      if  textBox    null          textBox SelectAll       private static int LastHashCode  private static void GotFocus object sender  RoutedEventArgs e        var textBox   e OriginalSource as TextBox      if  textBox    null          LastHashCode   textBox GetHashCode

User · Answer

If there s an event that deselects text during the OnFocus mouse up  I usually just delay the select all   private void TextBox GotFocus object sender  RoutedEventArgs e        if  TextBox Text    null                    Task Run      gt                        Dispatcher Invoke                  async      gt                        await Task Delay 100                       TextBox SelectAll

User · Answer

I searched a lot for the solution  I found couple of solutions to selectall But  the issue is when we do right click and do cut copy after selecting part of text from text box  it selects all even I selected part of text  To fix this here is the solution  Just add the below code in the keyboard select event  This worked for me   private static void SelectContentsChanged DependencyObject d  DependencyPropertyChangedEventArgs e        if  d is TextBox                TextBox textBox   d as TextBox          if   e NewValue as bool   GetValueOrDefault false                         textBox GotKeyboardFocus    OnKeyboardFocusSelectText                                     else                       textBox GotKeyboardFocus -  OnKeyboardFocusSelectText                       private static void OnKeyboardFocusSelectText object sender  KeyboardFocusChangedEventArgs e        if  e KeyboardDevice IsKeyDown Key Tab             TextBox sender  SelectAll

User · Answer

I have used Nils  answer but converted to more flexible   public enum SelectAllMode             lt summary gt           On first focus  it selects all then leave off textbox and doesn t check again          lt  summary gt      OnFirstFocusThenLeaveOff   0            lt summary gt           On first focus  it selects all then never selects          lt  summary gt      OnFirstFocusThenNever   1            lt summary gt          Selects all on every focus          lt  summary gt      OnEveryFocus   2            lt summary gt          Never selects text  WPF s default attitude           lt  summary gt      Never   4     public partial class TextBox   DependencyObject       public static readonly DependencyProperty SelectAllModeProperty   DependencyProperty RegisterAttached           SelectAllMode           typeof SelectAllMode            typeof TextBox           new PropertyMetadata SelectAllModePropertyChanged         private static void SelectAllModePropertyChanged DependencyObject d  DependencyPropertyChangedEventArgs e                if  d is System Windows Controls TextBox                        var textBox   d as System Windows Controls TextBox               if  e NewValue    null                                textBox GotKeyboardFocus    OnKeyboardFocusSelectText                  textBox PreviewMouseLeftButtonDown    OnMouseLeftButtonDown                            else                               textBox GotKeyboardFocus -  OnKeyboardFocusSelectText                  textBox PreviewMouseLeftButtonDown -  OnMouseLeftButtonDown                                     private static void OnMouseLeftButtonDown object sender  MouseButtonEventArgs e                DependencyObject dependencyObject   GetParentFromVisualTree e OriginalSource            if  dependencyObject    null              return           var textBox    System Windows Controls TextBox dependencyObject          if   textBox IsKeyboardFocusWithin                        textBox Focus                e Handled   true                       private static DependencyObject GetParentFromVisualTree object source                DependencyObject parent   source as UIElement          while  parent    null  amp  amp    parent is System Windows Controls TextBox                         parent   VisualTreeHelper GetParent parent                      return parent             private static void OnKeyboardFocusSelectText object sender  KeyboardFocusChangedEventArgs e                var textBox   e OriginalSource as System Windows Controls TextBox          if  textBox    null  return           var selectAllMode   GetSelectAllMode textBox            if  selectAllMode    SelectAllMode Never                        textBox SelectionStart   0              textBox SelectionLength   0                    else             textBox SelectAll             if  selectAllMode    SelectAllMode OnFirstFocusThenNever              SetSelectAllMode textBox  SelectAllMode Never           else if  selectAllMode    SelectAllMode OnFirstFocusThenLeaveOff              SetSelectAllMode textBox  null               AttachedPropertyBrowsableForChildrenAttribute IncludeDescendants   false        AttachedPropertyBrowsableForType typeof System Windows Controls TextBox        public static SelectAllMode  GetSelectAllMode DependencyObject  object                return  SelectAllMode  object GetValue SelectAllModeProperty              public static void SetSelectAllMode DependencyObject  object  SelectAllMode  value                 object SetValue SelectAllModeProperty  value             In XAML  you can use like one of these    lt  -- On first focus  it selects all then leave off textbox and doesn t check again -- gt   lt TextBox attprop TextBox SelectAllMode  OnFirstFocusThenLeaveOff    gt    lt  -- On first focus  it selects all then never selects -- gt   lt TextBox attprop TextBox SelectAllMode  OnFirstFocusThenNever    gt    lt  -- Selects all on every focus -- gt   lt TextBox attprop TextBox SelectAllMode  OnEveryFocus    gt    lt  -- Never selects text  WPF s default attitude  -- gt   lt TextBox attprop TextBox SelectAllMode  Never    gt

User · Answer

I realize this is very old  but here is my solution which is based on the expressions microsoft interactivity and interactions name spaces   First  I followed the instructions at this link to place interactivity triggers into a style   Then it comes down to this   lt Style x Key  baseTextBox  TargetType  TextBox  gt     lt Setter Property  gint InteractivityItems Template  gt       lt Setter Value gt         lt gint InteractivityTemplate gt           lt gint InteractivityItems gt             lt gint InteractivityItems Triggers gt               lt i EventTrigger EventName  GotKeyboardFocus  gt                 lt ei CallMethodAction MethodName  SelectAll   gt               lt  i EventTrigger gt               lt i EventTrigger EventName  PreviewMouseLeftButtonDown  gt                 lt ei CallMethodAction MethodName  TextBox PreviewMouseLeftButtonDown                  TargetObject   Binding ElementName HostElementName    gt               lt  i EventTrigger gt             lt  gint InteractivityItems Triggers gt           lt  gint InteractivityItems gt         lt  gint InteractivityTemplate gt       lt  Setter Value gt     lt  Setter gt   lt  Style gt    and this  public void TextBox PreviewMouseLeftButtonDown object sender  MouseButtonEventArgs e      TextBox tb   e Source as TextBox    if  tb    null   amp  amp   tb IsKeyboardFocusWithin    false           tb Focus        e Handled   true          In my case  I have a user control where the text boxes are that has a code-behind  The code-behind has the handler function  I gave my user control a name in XAML  and I am using that name for the element  This is working perfectly for me  Simply apply the style to any TextBox where you would like to have all the text selected when you click in the TextBox   The first CallMethodAction calls the text box s SelectAll method when the GotKeyboardFocus event on the TextBox fires   I hope this helps

User · Answer

For those interested in Donnelle s Groky s approach  but want a click to the right of the last character  but still within the TextBox  to place the caret at the end of the entered text  I ve come up with this solution   int GetRoundedCharacterIndexFromPoint TextBox textBox  Point clickedPoint        int position   textBox GetCharacterIndexFromPoint clickedPoint  true           Check if the clicked point is actually closer to the next character        or if it exceeds the righmost character in the textbox         in this case return increase the position by 1      Rect charLeftEdge   textBox GetRectFromCharacterIndex position  false       Rect charRightEdge   textBox GetRectFromCharacterIndex position  true       double charWidth   charRightEdge X - charLeftEdge X      if  clickedPoint X   charWidth   2  gt  charLeftEdge X   charWidth  position         return position     void SelectivelyIgnoreMouseButton object sender  MouseButtonEventArgs e           Find the TextBox     DependencyObject parent   e OriginalSource as UIElement      while  parent    null  amp  amp    parent is TextBox           parent   VisualTreeHelper GetParent parent        if  parent    null                var textBox    TextBox parent          if   textBox IsKeyboardFocusWithin                           If the text box is not yet focused  give it the focus and                stop further processing of this click event              textBox Focus                e Handled   true                    else                       int pos   GetRoundedCharacterIndexFromPoint textBox  e GetPosition textBox                textBox CaretIndex   pos                     void SelectAllText object sender  RoutedEventArgs e        var textBox   e OriginalSource as TextBox      if  textBox    null          textBox SelectAll        The GetRoundedCharacterIndexFromPoint method was taken from this post

User · Answer

WOW  After reading all the above I find myself overwhelmed and confused  I took what I thought I learned in this post and tried something completely different  To select the text in a TexTbox when it gets focus I use this   private void TextField GotFocus object sender  RoutedEventArgs e        TextBox tb    sender as Textbox       if tb    null                e Handled   true          tb Focus            tb SelectAll              Set the GotFocus property of the TexTbox to this method   Running the application and clicking once in the TexTbox highlights everything already in the TexTbox   If indeed  the objective is to select the text when the user clicks in the TexTbox  this seems simple and involves a whole lot less code  Just saying

User · Answer

I ve found none of the answers presented here mimic a standard Windows textbox  For instance  try to click in the white space between the last character of the textbox and the right side of the textbox  Most of the solutions here will always select the whole content  which makes it very difficult to append text to a textbox   The answer that I present here behaves better in this respect  It is a behavior  so it requires the System Windows Interactivity assembly from the Blend SDK   It could be rewritten using attached properties as well   public sealed class SelectAllTextOnFocusBehavior   Behavior lt TextBox gt        protected override void OnAttached                 base OnAttached            AssociatedObject PreviewMouseLeftButtonDown    AssociatedObject PreviewMouseLeftButtonDown             protected override void OnDetaching                 base OnDetaching            AssociatedObject PreviewMouseLeftButtonDown -  AssociatedObject PreviewMouseLeftButtonDown             void AssociatedObject PreviewMouseLeftButtonDown object sender  MouseButtonEventArgs e                   Find the textbox         DependencyObject parent   e OriginalSource as UIElement          while  parent    null  amp  amp    parent is TextBox               parent   VisualTreeHelper GetParent parent            var textBox   parent as TextBox          Debug Assert textBox    null            if  textBox IsFocused  return           textBox SelectAll            Keyboard Focus textBox           e Handled   true            This is based on code I ve found here

User · Answer

Here s a very good very simple solution on MSDN    lt TextBox     MouseDoubleClick  SelectAddress      GotKeyboardFocus  SelectAddress      PreviewMouseLeftButtonDown  SelectivelyIgnoreMouseButton    gt    Here s the code behind   private void SelectAddress object sender  RoutedEventArgs e        TextBox tb    sender as TextBox       if  tb    null                tb SelectAll             private void SelectivelyIgnoreMouseButton object sender      MouseButtonEventArgs e        TextBox tb    sender as TextBox       if  tb    null                if   tb IsKeyboardFocusWithin                        e Handled   true              tb Focus

User · Answer

Try this extension method to add the desired behaviour to any TextBox control  I havn t tested it extensively yet  but it seems to fulfil my needs   public static class TextBoxExtensions       public static void SetupSelectAllOnGotFocus this TextBox source                source GotFocus    SelectAll          source PreviewMouseLeftButtonDown    SelectivelyIgnoreMouseButton             private static void SelectAll object sender  RoutedEventArgs e                var textBox   e OriginalSource as TextBox          if  textBox    null              textBox SelectAll               private static void SelectivelyIgnoreMouseButton object sender  MouseButtonEventArgs e                var textBox    sender as TextBox           if  textBox    null                        if   textBox IsKeyboardFocusWithin                                e Handled   true                  textBox Focus

User · Answer

I think this works well   private void ValueText GotFocus object sender  RoutedEventArgs e        TextBox tb    TextBox e OriginalSource      tb Dispatcher BeginInvoke          new Action delegate                               tb SelectAll                    System Windows Threading DispatcherPriority Input       If you would like to implement it as an extension method   public static void SelectAllText this System Windows Controls TextBox tb        tb Dispatcher BeginInvoke          new Action delegate                       tb SelectAll                System Windows Threading DispatcherPriority Input       And in your GotFocus event   private void ValueText GotFocus object sender  RoutedEventArgs e        TextBox tb    TextBox e OriginalSource      tb SelectAllText        I discovered the solution above because several months ago I was looking for a way to set focus to a given UIElement  I discovered the the code below somewhere  credit is hereby given  and it works well  I post it even though it is not directly related to the OP s question because it demonstrates the same pattern of using Dispatcher to work with a UIElement      Sets focus to uiElement public static void DelayedFocus this UIElement uiElement        uiElement Dispatcher BeginInvoke      new Action delegate               uiElement Focusable   true          uiElement Focus            Keyboard Focus uiElement               DispatcherPriority Render

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In App xaml file    lt Application Resources gt       lt Style TargetType  TextBox  gt           lt EventSetter Event  GotKeyboardFocus  Handler  TextBox GotKeyboardFocus   gt       lt  Style gt   lt  Application Resources gt    In App xaml cs file   private void TextBox GotKeyboardFocus Object sender  KeyboardFocusChangedEventArgs e          TextBox sender  SelectAll        With this code you reach all TextBox in your application

User · Answer

This is by far the simplest solution   Add a global handler to the application  App xaml cs  and done  You are going to need only a few lines of code   protected override void OnStartup StartupEventArgs e        EventManager RegisterClassHandler typeof TextBox           TextBox GotFocusEvent          new RoutedEventHandler TextBox GotFocus         base OnStartup e       So use the EventManager class to register a global event handler against a type  TextBox   The actual handler is dead simple   private void TextBox GotFocus object sender  RoutedEventArgs e         sender as TextBox  SelectAll        Check here  WPF TextBox SelectAll on Focus  Hope it helps

User · Answer

This seems to work well for me  It s basically a recap of some earlier posts  I just put this into my MainWindow xaml cs file in the constructor  I create two handlers  one for keyboard  and one for the mouse  and funnel both events into the same function  HandleGotFocusEvent  which is defined right after the constructor in the same file   public MainWindow        InitializeComponent        EventManager RegisterClassHandler typeof TextBox          UIElement GotKeyboardFocusEvent        new RoutedEventHandler HandleGotFocusEvent   true      EventManager RegisterClassHandler typeof TextBox         UIElement GotMouseCaptureEvent        new RoutedEventHandler HandleGotFocusEvent   true        private void HandleGotFocusEvent object sender  RoutedEventArgs e       if  sender is TextBox         sender as TextBox  SelectAll

User · Answer

We have it so the first click selects all  and another click goes to cursor  our application is designed for use on tablets with pens    You might find it useful   public class ClickSelectTextBox   TextBox       public ClickSelectTextBox                 AddHandler PreviewMouseLeftButtonDownEvent             new MouseButtonEventHandler SelectivelyIgnoreMouseButton   true           AddHandler GotKeyboardFocusEvent             new RoutedEventHandler SelectAllText   true           AddHandler MouseDoubleClickEvent             new RoutedEventHandler SelectAllText   true              private static void SelectivelyIgnoreMouseButton object sender                                                        MouseButtonEventArgs e                   Find the TextBox         DependencyObject parent   e OriginalSource as UIElement          while  parent    null  amp  amp    parent is TextBox               parent   VisualTreeHelper GetParent parent            if  parent    null                        var textBox    TextBox parent              if   textBox IsKeyboardFocusWithin                                   If the text box is not yet focussed  give it the focus and                    stop further processing of this click event                  textBox Focus                    e Handled   true                                     private static void SelectAllText object sender  RoutedEventArgs e                var textBox   e OriginalSource as TextBox          if  textBox    null              textBox SelectAll

User · Answer

Taken from here   Register global event handler in App xaml cs file    protected override void OnStartup StartupEventArgs e        EventManager RegisterClassHandler typeof TextBox  TextBox GotFocusEvent      new RoutedEventHandler TextBox GotFocus         base OnStartup e       Then the handler is as simple as    private void TextBox GotFocus object sender  RoutedEventArgs e         sender as TextBox  SelectAll

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Here is the C  version of the answer posted by  Nasenbaer  private delegate void TextBoxSelectAllDelegate object sender    private void TextBoxSelectAll object sender         sender as System Windows Controls TextBox  SelectAll       private void MyTextBox GotFocus object sender  System Windows RoutedEventArgs e        TextBoxSelectAllDelegate d   TextBoxSelectAll       this Dispatcher BeginInvoke d          System Windows Threading DispatcherPriority ApplicationIdle  sender       whereas MyTextBox GotFocus is the event handler assigned to the GotFocus event of MyTextBox

User · Answer

Try putting this in the constructor of whatever control is housing your textbox   Loaded     sender  e    gt        MoveFocus new TraversalRequest FocusNavigationDirection Next        myTextBox SelectAll

User · Answer

I solved this problem using an Attached Behavior rather than an Expression Behavior as in Sergey s answer  This means I don t need a dependency on System Windows Interactivity in the Blend SDK  public class TextBoxBehavior       public static bool GetSelectAllTextOnFocus TextBox textBox                return  bool textBox GetValue SelectAllTextOnFocusProperty              public static void SetSelectAllTextOnFocus TextBox textBox  bool value                textBox SetValue SelectAllTextOnFocusProperty  value              public static readonly DependencyProperty SelectAllTextOnFocusProperty           DependencyProperty RegisterAttached               quot SelectAllTextOnFocus quot               typeof  bool               typeof  TextBoxBehavior               new UIPropertyMetadata false  OnSelectAllTextOnFocusChanged         private static void OnSelectAllTextOnFocusChanged DependencyObject d  DependencyPropertyChangedEventArgs e                var textBox   d as TextBox          if  textBox    null  return           if  e NewValue is bool    false  return           if   bool  e NewValue                        textBox GotFocus    SelectAll              textBox PreviewMouseDown    IgnoreMouseButton                    else                       textBox GotFocus -  SelectAll              textBox PreviewMouseDown -  IgnoreMouseButton                       private static void SelectAll object sender  RoutedEventArgs e                var textBox   e OriginalSource as TextBox          if  textBox    null  return          textBox SelectAll               private static void IgnoreMouseButton object sender  System Windows Input MouseButtonEventArgs e                var textBox   sender as TextBox          if  textBox    null      textBox IsReadOnly  amp  amp  textBox IsKeyboardFocusWithin   return           e Handled   true          textBox Focus             You can then use it in your XAML like this   lt TextBox Text  quot Some Text quot  behaviors TextBoxBehavior SelectAllTextOnFocus  quot True quot   gt   I blogged about it here

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Here is an attempt to solve some of the problems with other solutions    Using right click context menu for cut copy past selects all text even if you didn t select it all  When returning from right click context menu  all text is always selected  When returning to the application with Alt Tab  all text is always selected  When trying to select only part of the text on the first click  all is always selected  unlike Google chromes address bar for example     The code I wrote is configurable  You can  choose on what actions the select all behavior should occur by setting three readonly fields  SelectOnKeybourdFocus  SelectOnMouseLeftClick  SelectOnMouseRightClick   The downside of this solution is that it s more complex and static state is stored  Its seems like an ugly struggle with the defaults behavior of the TextBox control  Still  it works and all the code is hidden in the Attached Property container class   public static class TextBoxExtensions          Configuration fields to choose on what actions the select all behavior should occur      static readonly bool SelectOnKeybourdFocus   true      static readonly bool SelectOnMouseLeftClick   true      static readonly bool SelectOnMouseRightClick   true          Remembers a right click context menu that is opened      static ContextMenu ContextMenu   null          Remembers if the first action on the TextBox is mouse down      static bool FirstActionIsMouseDown   false       public static readonly DependencyProperty SelectOnFocusProperty           DependencyProperty RegisterAttached  SelectOnFocus   typeof bool   typeof TextBoxExtensions   new PropertyMetadata false  new PropertyChangedCallback OnSelectOnFocusChanged           AttachedPropertyBrowsableForChildren IncludeDescendants   false        AttachedPropertyBrowsableForType typeof TextBox        public static bool GetSelectOnFocus DependencyObject obj                return  bool obj GetValue SelectOnFocusProperty              public static void SetSelectOnFocus DependencyObject obj  bool value                obj SetValue SelectOnFocusProperty  value              private static void OnSelectOnFocusChanged DependencyObject d  DependencyPropertyChangedEventArgs e                if    d is TextBox textBox   return           if  GetSelectOnFocus textBox                            Register events             textBox PreviewMouseDown    TextBox PreviewMouseDown              textBox PreviewMouseUp    TextBox PreviewMouseUp              textBox GotKeyboardFocus    TextBox GotKeyboardFocus              textBox LostKeyboardFocus    TextBox LostKeyboardFocus                    else                          Unregister events             textBox PreviewMouseDown -  TextBox PreviewMouseDown              textBox PreviewMouseUp -  TextBox PreviewMouseUp              textBox GotKeyboardFocus -  TextBox GotKeyboardFocus              textBox LostKeyboardFocus -  TextBox LostKeyboardFocus                       private static void TextBox PreviewMouseDown object sender  MouseButtonEventArgs e                if    sender is TextBox textBox   return              If mouse clicked and focus was not in text box  remember this is the first click             This will enable to prevent select all when the text box gets the keyboard focus             right after the mouse down event          if   textBox IsKeyboardFocusWithin                        FirstActionIsMouseDown   true                       private static void TextBox PreviewMouseUp object sender  MouseButtonEventArgs e                if    sender is TextBox textBox   return              Select all only if             1  SelectOnMouseLeftClick SelectOnMouseRightClick is true and left right button was clicked            3  This is the first click            4  No text is selected         if    SelectOnMouseLeftClick  amp  amp  e ChangedButton    MouseButton Left                   SelectOnMouseRightClick  amp  amp  e ChangedButton    MouseButton Right    amp  amp              FirstActionIsMouseDown  amp  amp              string IsNullOrEmpty textBox SelectedText                         textBox SelectAll                          It is not the first click          FirstActionIsMouseDown   false             private static void TextBox GotKeyboardFocus object sender  KeyboardFocusChangedEventArgs e                if    sender is TextBox textBox   return              Select all only if             1  SelectOnKeybourdFocus is true            2  Focus was not previously out of the application  e OldFocus    null             3  The mouse was pressed down for the first after on the text box            4  Focus was not previously in the context menu         if  SelectOnKeybourdFocus  amp  amp              e OldFocus    null  amp  amp               FirstActionIsMouseDown  amp  amp               IsObjectInObjectTree e OldFocus as DependencyObject  ContextMenu                         textBox SelectAll                          Forget ContextMenu         ContextMenu   null             private static void TextBox LostKeyboardFocus object sender  KeyboardFocusChangedEventArgs e                if    sender is TextBox textBox   return              Remember ContextMenu  if opened          ContextMenu   e NewFocus as ContextMenu              Forget selection when focus is lost if             1  Focus is still in the application            2  The context menu was not opened         if  e NewFocus    null              amp  amp  ContextMenu    null                        textBox SelectionLength   0                          Helper function to look if a DependencyObject is contained in the visual tree of another object     private static bool IsObjectInObjectTree DependencyObject searchInObject  DependencyObject compireToObject                while  searchInObject    null  amp  amp  searchInObject    compireToObject                        searchInObject   VisualTreeHelper GetParent searchInObject                      return searchInObject    null            To attache the Attached Property to a TextBox  all you need to do is add the xml namespace  xmlns  of the Attached Property and then use it like this    lt TextBox attachedprop TextBoxExtensions SelectOnFocus  True   gt    Some notes about this solution    To override the default behavior of a mouse down event and enable selecting only part of the text on the first click  all text is selected on mouse up event  I had to deal with the fact the the TextBox remembers its selection after it loses focus  I actually have overridden this behavior  I had to remember if a mouse button down is the first action on the TextBox  FirstActionIsMouseDown static field   I had to remember the context menu opened by a right click  ContextMenu static field     The only side effect I found is when SelectOnMouseRightClick is true  Sometimes the right-click context menu flickers when its opened and right-clicking on a blank are in the TextBox does not do  select all

User · Answer

After googling and testing  I ve found a simple solution that worked for me   You need to add an event handler to the Loaded event of your container window   private void yourwindow Loaded object sender  RoutedEventArgs e        EventManager RegisterClassHandler typeof TextBox           TextBox PreviewMouseLeftButtonDownEvent          new RoutedEventHandler SelectivelyIgnoreMouseButton        Next  you have to create the handler to the referenced RoutedEventHandler in previous code   private void SelectivelyIgnoreMouseButton object sender  RoutedEventArgs e        TextBox tb    sender as TextBox       if  tb    null                if   tb IsKeyboardFocusWithin                        e Handled   true              tb Focus                        Now  you can add the SelectAll   command on GotFocus event handlers to any TextBox controls separately   private void myTextBox GotFocus object sender  RoutedEventArgs e         sender as TextBox  SelectAll        Your text now is selected on focus   Adapted from Dr  WPF solution  MSDN Forums

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This simple implementation works perfectly for me   void TextBox GotFocus object sender  RoutedEventArgs e          TextBox  sender  SelectAll       void TextBox PreviewMouseDown object sender  MouseButtonEventArgs e        var TextBox    TextBox  sender      if   TextBox IsKeyboardFocusWithin                TextBox Focus            e Handled   true            To apply it to all TextBox s  put the following code after InitializeComponent     EventManager RegisterClassHandler typeof TextBox   TextBox GotFocusEvent  new RoutedEventHandler TextBox GotFocus    EventManager RegisterClassHandler typeof TextBox   TextBox PreviewMouseDownEvent  new MouseButtonEventHandler TextBox PreviewMouseDown

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region TextBoxIDCard selection private bool textBoxIDCardGotFocus   false  private void TextBoxIDCard GotFocus object sender  RoutedEventArgs e        this TextBoxIDCard SelectAll       private void TextBoxIDCard LostFocus object sender  RoutedEventArgs e        textBoxIDCardGotFocus   false     private void TextBoxIDCard PreviewMouseDown object sender  MouseButtonEventArgs e        if  textBoxIDCardGotFocus    false                e Handled   true          this TextBoxIDCard Focus            textBoxIDCardGotFocus   true            endregion

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Donnelle s answer works the best  but having to derive a new class to use it is a pain    Instead of doing that I register handlers the handlers in App xaml cs for all TextBoxes in the application  This allows me to use a Donnelle s answer with standard TextBox control   Add the following methods to your App xaml cs   public partial class App   Application       protected override void OnStartup StartupEventArgs e                    Select the text in a TextBox when it receives focus          EventManager RegisterClassHandler typeof TextBox   TextBox PreviewMouseLeftButtonDownEvent              new MouseButtonEventHandler SelectivelyIgnoreMouseButton            EventManager RegisterClassHandler typeof TextBox   TextBox GotKeyboardFocusEvent               new RoutedEventHandler SelectAllText            EventManager RegisterClassHandler typeof TextBox   TextBox MouseDoubleClickEvent              new RoutedEventHandler SelectAllText            base OnStartup e               void SelectivelyIgnoreMouseButton object sender  MouseButtonEventArgs e                   Find the TextBox         DependencyObject parent   e OriginalSource as UIElement          while  parent    null  amp  amp    parent is TextBox               parent   VisualTreeHelper GetParent parent            if  parent    null                        var textBox    TextBox parent              if   textBox IsKeyboardFocusWithin                                   If the text box is not yet focused  give it the focus and                    stop further processing of this click event                  textBox Focus                    e Handled   true                                     void SelectAllText object sender  RoutedEventArgs e                var textBox   e OriginalSource as TextBox          if  textBox    null              textBox SelectAll

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Here are the Blend behaviors implementing the answer solution for your convenience   One for attaching to a single TextBox   public class SelectAllTextOnFocusBehavior   Behavior lt TextBox gt        protected override void OnAttached                 base OnAttached            AssociatedObject GotKeyboardFocus    AssociatedObjectGotKeyboardFocus          AssociatedObject GotMouseCapture    AssociatedObjectGotMouseCapture          AssociatedObject PreviewMouseLeftButtonDown    AssociatedObjectPreviewMouseLeftButtonDown             protected override void OnDetaching                 base OnDetaching            AssociatedObject GotKeyboardFocus -  AssociatedObjectGotKeyboardFocus          AssociatedObject GotMouseCapture -  AssociatedObjectGotMouseCapture          AssociatedObject PreviewMouseLeftButtonDown -  AssociatedObjectPreviewMouseLeftButtonDown             private void AssociatedObjectGotKeyboardFocus object sender          System Windows Input KeyboardFocusChangedEventArgs e                AssociatedObject SelectAll               private void AssociatedObjectGotMouseCapture object sender          System Windows Input MouseEventArgs e                AssociatedObject SelectAll                  private void AssociatedObjectPreviewMouseLeftButtonDown object sender  MouseButtonEventArgs e                if  AssociatedObject IsKeyboardFocusWithin                        AssociatedObject Focus                e Handled   true                      And one for attaching to the root of a container containing multiple TextBox es   public class SelectAllTextOnFocusMultiBehavior   Behavior lt UIElement gt        protected override void OnAttached                 base OnAttached            AssociatedObject GotKeyboardFocus    HandleKeyboardFocus          AssociatedObject GotMouseCapture    HandleMouseCapture             protected override void OnDetaching                 base OnDetaching            AssociatedObject GotKeyboardFocus -  HandleKeyboardFocus          AssociatedObject GotMouseCapture -  HandleMouseCapture             private static void HandleKeyboardFocus object sender          System Windows Input KeyboardFocusChangedEventArgs e                var txt   e NewFocus as TextBox          if  txt    null              txt SelectAll               private static void HandleMouseCapture object sender          System Windows Input MouseEventArgs e                var txt   e OriginalSource as TextBox          if  txt    null              txt SelectAll

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An easy way to override the mouseDown and select all after doubleclick is   public class DoubleClickTextBox  TextBox        public override void EndInit                 base EndInit                           protected override void OnMouseEnter System Windows Input MouseEventArgs e                base OnMouseEnter e           this Cursor   Cursors Arrow            protected override void OnMouseDown System Windows Input MouseButtonEventArgs e                    protected override void OnMouseDoubleClick System Windows Input MouseButtonEventArgs e                base OnMouseDown e           this SelectAll

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I had same problem  In VB Net it works easy that way   VB XAML    lt TextBox x Name  txtFilterFrequency    gt    Codehind   Private Sub txtFilterText GotFocus sender As System Object  e As System Windows RoutedEventArgs  Handles txtFilterText GotFocus     Me Dispatcher BeginInvoke Sub                                     txtFilterText SelectAll                                 End Sub  DispatcherPriority ApplicationIdle  Nothing  End Sub   C   thanks to ViRuSTriNiTy   private delegate void TextBoxSelectAllDelegate object sender    private void TextBoxSelectAll object sender         sender as System Windows Controls TextBox  SelectAll       private void MyTextBox GotFocus object sender  System Windows RoutedEventArgs e        TextBoxSelectAllDelegate d   TextBoxSelectAll       this Dispatcher BeginInvoke d          System Windows Threading DispatcherPriority ApplicationIdle  sender

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The simplist and perfect solution  is to use a timer to select all text  20ms after textbox got focus  Dim WithEvents Timer As New DispatcherTimer   Set the interval  Timer Interval   TimeSpan FromMilliseconds 20  respond to events  I am inheriting the TextBox control here  so I am overriding its events  Protected Overrides Sub OnGotFocus e As RoutedEventArgs          Timer Start           MyBase OnGotFocus e      End Sub       Private Sub Timer Tick sender As Object  e As EventArgs  Handles Timer Tick         Timer Stop           Me SelectAll       End Sub  And that is all

User · Answer

I have chosen part of Donnelle s answer  skipped the double-click  for I think this a more natural  However  like gcores I dislike the need to create a derived class  But I also don t like gcores OnStartup method  And I need this on a  quot generally but not always quot  basis  I have Implemented this as an attached DependencyProperty so I can set local SelectTextOnFocus Active    quot True quot  in xaml  I find this way the most pleasing  using System Windows  using System Windows Controls  using System Windows Input  using System Windows Media   public class SelectTextOnFocus   DependencyObject       public static readonly DependencyProperty ActiveProperty   DependencyProperty RegisterAttached           quot Active quot           typeof bool           typeof SelectTextOnFocus           new PropertyMetadata false  ActivePropertyChanged         private static void ActivePropertyChanged DependencyObject d  DependencyPropertyChangedEventArgs e                if  d is TextBox                        TextBox textBox   d as TextBox              if   e NewValue as bool   GetValueOrDefault false                                 textBox GotKeyboardFocus    OnKeyboardFocusSelectText                  textBox PreviewMouseLeftButtonDown    OnMouseLeftButtonDown                            else                               textBox GotKeyboardFocus -  OnKeyboardFocusSelectText                  textBox PreviewMouseLeftButtonDown -  OnMouseLeftButtonDown                                     private static void OnMouseLeftButtonDown object sender  MouseButtonEventArgs e                DependencyObject dependencyObject   GetParentFromVisualTree e OriginalSource            if  dependencyObject    null                        return                     var textBox    TextBox dependencyObject          if   textBox IsKeyboardFocusWithin                        textBox Focus                e Handled   true                       private static DependencyObject GetParentFromVisualTree object source                DependencyObject parent   source as UIElement          while  parent    null  amp  amp    parent is TextBox                         parent   VisualTreeHelper GetParent parent                      return parent             private static void OnKeyboardFocusSelectText object sender  KeyboardFocusChangedEventArgs e                TextBox textBox   e OriginalSource as TextBox          if  textBox    null                        textBox SelectAll                          AttachedPropertyBrowsableForChildrenAttribute IncludeDescendants   false        AttachedPropertyBrowsableForType typeof TextBox        public static bool GetActive DependencyObject  object                return  bool   object GetValue ActiveProperty              public static void SetActive DependencyObject  object  bool value                 object SetValue ActiveProperty  value            For my  quot general but not always quot  feature I set this Attache Property to True in a  global  TextBox Style  This way  quot selecting the Text quot  is always  quot on quot   but I can disable it on a per-textbox-basis

User · Answer

Don t know why it loses the selection in the GotFocus event   But one solution is to do the selection on the GotKeyboardFocus and the GotMouseCapture events  That way it will always work

[.net] How to automatically select all text on focus in WPF TextBox?

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