How do I Set Focus in My Custom User Control?

When you create a custom user control, it typically contains child user interface elements. To provide a proper "Focus" experience at run time, you need to do the following:

Select your user control in design mode and check the Focusable check box
Create a handler method for your user control's GotFocus event. In the event handler method, add a line of code that sets focus to the child control you want to initially receive focus. For example:
```
private void AutoCompleteTextBox_GotFocus(object sender, RoutedEventArgs e)
```
```
{
```
```
    this.txtTextBox.Focus();
```
```
}
```