TextBox loses focus on Key Command

Question

In my WPF application I have a text box control. The text box control is located in a UserControl which in turn has a View Model class. In my VM class I have a Command, which get executed either when a button is clicked in UserControl or when the Enter key is pressed. My problem is that when I press Enter, the text box loses focus and I have to click on the text box to get it focused again. What can I do to make the textbox keep focus when the key is pressed ?

I try to make a sketch on what I'm using right now:

<Window>  
    <uc:DesignPanel ... />
    <uc:CommandPrompt ... />  
</Window>

<UserControl Name=CommandPrompt ...>
    <StackPanel>
        <TextBox Name="tb_commands" />
        <Button Name="btn_process" FocusManager.FocusedElement="{Binding ElementName=tb_commands}" />
    </StackPanel>      
</UserControl>

The DesignPanel user control in turn contains other user controls (UCOperands). The UCOperand basically looks like this:

<UserControl Name="UCOperand" Focusable="true">  
    <UserControl.InputBindings ... />  
</UserControl>

Note here that I have set Focusable="true" on the UCOperand, this is needed because otherwise the user cannot invoke the input commands defined on this contrl. If I remove this property or set it to false, then everything works just as I expect, e.g. when I press Enter while I'm editing the "tb_commands" text box or click on "btn_process" button the focus is kept on the text box. But as it is now, whenever hit Enter or click on the button, the tb_commands loses focus.

Thanks in advance.

Zamboni Zamboni · Accepted Answer · 2010-06-25T02:54:31

Add a Storyboard with a short duration to your Window and use the Completed event to set focus to the Textbox (see bottom of my sample).

<Window x:Class="TextboxFocus.Views.MainView"
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  xmlns:uc="clr-namespace:TextboxFocus.Views" 
  KeyDown="Window_KeyDown"
  Title="Main Window" Height="400" Width="800">

  <Window.Triggers>
      <EventTrigger RoutedEvent="FrameworkElement.Loaded">
          <BeginStoryboard>
              <Storyboard BeginTime="0:0:1" Completed="Go_Completed">
              </Storyboard>
          </BeginStoryboard>
      </EventTrigger>
  </Window.Triggers>
  <DockPanel>
      <uc:CommandPrompt x:Name="UC" >
      </uc:CommandPrompt>
  </DockPanel>
</Window>


<UserControl x:Class="TextboxFocus.Views.CommandPrompt"
  Name="UCOperand" 
  Focusable="true"
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  Height="300" Width="300">
  <Grid>
    <Grid.RowDefinitions>
        <RowDefinition/>
        <RowDefinition/>
    </Grid.RowDefinitions>
    <TextBox Grid.Row="0" 
             x:Name="GoTextbox"/>
    <Button Grid.Row="1"  
        Content="Go"  
        FocusManager.FocusedElement="{Binding ElementName=GoTextbox}" 
        Command="{Binding GoCommand}" />
  </Grid>
</UserControl>


public partial class MainView : Window
{
  MainViewModel _mvm = new MainViewModel();

  public MainView()
  {
     InitializeComponent();

     this.DataContext = _mvm;
  }

  private void Window_KeyDown(object sender, KeyEventArgs e)
  {
     // trap the F5/Enter key and execute the query....
     if (e.Key == Key.Enter)
     {
        _mvm.GoCommand.Execute(null);
        e.Handled = true;
     }
  }

  // set focus here
  private void Go_Completed(object sender, EventArgs e)
  {
     UC.GoTextbox.Focus();
  }
}

TextBox loses focus on Key Command

2 Answers