How Do I Give a Textbox Focus in Silverlight?

Question

In my Silverlight application, I can't seem to bring focus to a TextBox control. On the recommendation of various posts, I've set the IsTabStop property to True and I'm using TextBox.Focus(). Though the UserControl_Loaded event is firing, the TextBox control isn't getting focus. I've included my very simple code below. What am I missing? Thanks.

Page.xaml

<UserControl x:Class="TextboxFocusTest.Page"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    Loaded="UserControl_Loaded" 
    Width="400" Height="300">

    <Grid x:Name="LayoutRoot" Background="White">        
        <StackPanel Width="150" VerticalAlignment="Center">            
            <TextBox x:Name="RegularTextBox" IsTabStop="True" />    
        </StackPanel>        
    </Grid>
</UserControl>

Page.xaml.cs

using System.Windows;
using System.Windows.Controls;

namespace PasswordTextboxTest
{
    public partial class Page : UserControl
    {
        public Page()
        {
            InitializeComponent();
        }

        private void UserControl_Loaded(object sender, RoutedEventArgs e)
        {
            RegularTextBox.Focus();
        }
    }
}

Answer 1

You code to set the focus is correct since if you add a button that calls the same code it works perfectly:

<StackPanel Width="150" VerticalAlignment="Center">
    <TextBox x:Name="RegularTextBox" IsTabStop="True" />
    <Button Click="UserControl_Loaded">
        <TextBlock Text="Test"/>
    </Button>
</StackPanel>

So I'm assuming this is something to do with Focus() requiring some kind of user interaction. I couldn't get it to work with a MouseMove event on the UserControl, but putting a KeyDown event to set the focus works (although the template doesn't update to the focused template).

Width="400" Height="300" Loaded="UserControl_Loaded" KeyDown="UserControl_KeyDown">

Seems like a bug to me....

Answer 2

Are you sure you're not really getting focus? There's a known bug in Beta 2 where you'll get focus and be able to type but you won't get the caret or the border. The workaround is to call UpdateLayout() on the textbox right before you call Focus().

Answer 3

I forgot one thing...I haven't found a way to force focus to your Silverlight application on the page reliably (it will work on some browsers and not on others).

So it may be that the Silverlight app itself doesn't have focus. I usually trick the user into clicking a button or something similar before I start expecting keyboard input to make sure that the silverlight app has focus.

Answer 4

I would try adding a DispatcherTimer on the UserLoaded event that executes the Focus method a few milliseconds after the whole control has loaded; maybe the problem is there.

Answer 5

I found this on silverlight.net, and was able to get it to work for me by adding a call to System.Windows.Browser.HtmlPage.Plugin.Focus() prior to calling RegularTextBox.Focus():

   private void UserControl_Loaded(object sender, RoutedEventArgs e)
   {        
      System.Windows.Browser.HtmlPage.Plugin.Focus();
      RegularTextBox.Focus();
   }

Answer 6

Calling System.Windows.Browser.HtmlPage.Plugin.Focus(); worked for me as well!

Answer 7

For out-of-browser apps the System.Windows.Browser.HtmlPage.Plugin.Focus(); doesn't exist.

See my question here for other ideas.

Answer 8

thanks Santiago Palladino Dispatcher worked for me perfectly. What I am doing is:

this.Focus(); then Dispatcher.BeginInvoke(() => { tbNewText.Focus();});

Answer 9

Plugin.Focus(); 

didn't work for me.

Calling

 Dispatcher.BeginInvoke(() => { tbNewText.Focus();});

From the Load event worked.

Answer 10

I also needed to call

Deployment.Current.Dispatcher.BeginInvoke(() => myTextbox.Focus());

interestingly this call is happening inside an event handler when I mouseclick on a TextBlock, collapse the TextBlock and make the TextBox Visible. If I don't follow it by a dispatcher.BeginInvoke it won't get focus.

-Mike