WPF - Why isn't Keyboard.Focus() working?

Question

have a TextBox item (MyTextBox) on a TabItem control. I have code that looks as follows:

MyTextBox.Focus();
Keyboard.Focus(MyTextBox);

When I run this code through the debugger I see the following after the lines are executed:

MyTextBox.IsFocused = true
MyTextBox.IsKeyboardFocused = false

Can anyone tell me why the textbox isn't receiving keyboard focus? It's just a standard TextBox control that is enabled.

Just to be sure. Is the TabItem you say this control on Visible when this call is made? I think the control must be visible for this property to bet set. — Matt, Feb 01 '11 at 21:35
I'm unable to reproduce this. Both `IsFocused` and `IsKeyboardFocused` comes out as True — Fredrik Hedblad, Feb 01 '11 at 22:06
@RandyMinder: Hi! do you found what's the problem? i have same problem. your accepted answer doesn't solve my issue. thank you — Jalal, Mar 27 '12 at 08:32
I'm also looking for solution this is work for me. https://stackoverflow.com/a/30571255/10882532 — Prince Kumar, Nov 22 '19 at 07:31

score 10 · Answer 1 · edited Sep 26 '12 at 12:34

When you try to set Focus to an element besides the things enumerated above by our coleague, you must also know that WPF does not allow cross threaded operations.

In some cases this exception is not raised like in the Focus method call case. What I've done to fix this issue is to call all the code that involves Keyboards focus in an action.

This action is ran inside the control dispatcher to make sure that my code is not being executed from another thread than the UI thread (e.g. timer event or an event raised from another thread):

[UIElement].Dispatcher.BeginInvoke(
      new Action(
         delegate{
             /// put your Focus code here
         }
      )
);

score 8 · Accepted Answer · edited Feb 01 '11 at 22:12

8

MyTextBox.IsKeyboardFocused is false because you are looking at it under debugger and the keyboard focus is probably in your Visual Studio... Try debugging focus without breakpoints (e.g. Debug.Write or trace brakepoints) to see actual values of MyTextBox.IsKeyboardFocused in runtime.

Also notice that Focus() method returns boolean value that indicates whether focus was successfully set. Does it return False in your case? If yes, I would suggest stepping into Focus() method in order to find out what is wrong.

edited Feb 01 '11 at 22:12

Fredrik Hedblad

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answered Feb 01 '11 at 21:45

Pavlo Glazkov

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Just want to point out that Control.focus() returns a boolean. Keyboard.Focus() returns an IInputElement (https://docs.microsoft.com/en-us/dotnet/api/system.windows.input.keyboard.focus) – bluegreen Oct 29 '20 at 23:26

score 6 · Answer 3 · edited Apr 16 '14 at 14:06

6

3 important properties must be true: IsVisible="True", Focusable="True". IsEnabled="True".

To be focusable, Focusable and IsEnabled must both be true.

http://msdn.microsoft.com/en-us/library/system.windows.uielement.focus.aspx

edited Apr 16 '14 at 14:06

slavoo

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answered Dec 19 '12 at 14:13

legrandviking

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Thanks for this, I had been trying to set the focus before a `Visibility` `Binding` had refreshed (solved with `MyTextBox.GetBindingExpression(VisibilityProperty).UpdateTarget();`). `MyTextBox.SelecAll()` is also magically working now. :) – Chris Mack Jul 17 '19 at 13:26

score 1 · Answer 4 · edited May 23 '17 at 12:02

The accepted answer here does not solve the problem of textboxes who dont gain focus, no matter what the debugger tells you. If you have and can write to your textbox, then you have it keyboard-focused.

I found this here solving the problem (and actually gaining focus, not just settings the values so it looks like focus in the debugger), it comes very close to Pavlov's answer but with the "Focus code" : Keyboard.Focus does not work on text box in WPF

score 1 · Answer 5 · answered Nov 19 '21 at 12:59

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This worked for me (had to do UpdateLayout, otherwise Focus() didn't work immediately after changing tab from script)

tabControl.SelectedIndex = 2;
this.UpdateLayout();
txtMyTextBox.Focus();

answered Nov 19 '21 at 12:59

mgear

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WPF - Why isn't Keyboard.Focus() working?

5 Answers5