Set Keyboard Focus

[David]

Client would like the keyboard cursor inside of the Combo Box when the Window loads. Calling "ComboBox.Focus()" does not place the keyboard cursor into the editable part of the ComboBox. Am I missing something simple? 

[Stefan Nenchev]

Hello David,

Calling the Focus method of the RadComboBox results in the cursor appearing if there is no SelectedItem set. Otherwise, the text within it will be selected and typing will override the value. Isn't this the behavior you are looking for? Please have a look at the sample. Do you see a different behavior in your setup? Please share more information on your scenario.

Regards,
Stefan Nenchev
Telerik by Progress

[David]

Hi Stefan,

Thanks for the reply. You are right. That is the behavior I'm looking for, however I am acquiring it through an Attached Property so I can control Focus through a View Model.

When I set the Attached Property "IsFocused" to "True", the TextBox portion of the ComboBox does not focus.

Here is the Attached Property for your reference.

public class RadComboBoxProperties
{
    public static DependencyProperty IsFocusedProperty = DependencyProperty.RegisterAttached("IsFocused", typeof( bool ), typeof( RadComboBoxProperties ), new UIPropertyMetadata( false, OnIsFocusedChanged ) );

    public static bool GetIsFocused( DependencyObject dependencyObject )
    {
        return (bool)dependencyObject.GetValue( IsFocusedProperty );
    }

    public static void SetIsFocused( DependencyObject dependencyObject, bool value )
    {
        dependencyObject.SetValue( IsFocusedProperty, value );
    }

    public static void OnIsFocusedChanged( DependencyObject dependencyObject, DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs )
    {
        RadComboBox comboBox = dependencyObject as RadComboBox;
        bool newValue = (bool)dependencyPropertyChangedEventArgs.NewValue;
        bool oldValue = (bool)dependencyPropertyChangedEventArgs.OldValue;
        if( newValue && !oldValue && !comboBox.IsFocused )
        {
            comboBox.Focus();
        }
    }
}

[Dilyan Traykov]

Hello David,

The reason the focus is not set to the RadComboBox properly is because when the Focus method is invoked, the control has not yet been fully loaded.

You will need to use a Dispatcher for this to work. Here's an interesting thread discussing a similar issue.

Therefore, you can define the OnIsFocusedChanged method like so:

public static void OnIsFocusedChanged(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs)
{
    RadComboBox comboBox = dependencyObject as RadComboBox;
    bool newValue = (bool)dependencyPropertyChangedEventArgs.NewValue;
    bool oldValue = (bool)dependencyPropertyChangedEventArgs.OldValue;
    if (newValue && !oldValue && !comboBox.IsFocused)
    {
        comboBox.Dispatcher.BeginInvoke((Action)(() =>
        {
            comboBox.Focus();
        }), DispatcherPriority.Render);
    }
}

Do let me know if this works for you.

Regards,
Dilyan Traykov
Telerik by Progress

[David]

Works like a charm. Thanks!