WPF - Set Focus when a button is clicked - No Code Behind

Question

Is there a way to set Focus from one control to another using WPF Triggers?

Like the following example:

Answer 1

This is the same as Ian Oakes' solution, but I made a couple minor changes.

1. The button type can be more general, namely ButtonBase, to handle more cases, such as ToggleButton.
2. The target type can also be more general, namely UIElement. Technically, this could be IInputElement, I suppose.
3. Made the event handler static so that it won't generate a runtime closure every time this is used.
4. [edit: 2019] Updated to use null-conditional and C#7 expression body syntax.

Many thanks to Ian.

---

public sealed class EventFocusAttachment
{
    public static UIElement GetTarget(ButtonBase b) => (UIElement)b.GetValue(TargetProperty);

    public static void SetTarget(ButtonBase b, UIElement tgt) => b.SetValue(TargetProperty, tgt);

    public static readonly DependencyProperty TargetProperty = DependencyProperty.RegisterAttached(
            "Target",
            typeof(UIElement),
            typeof(EventFocusAttachment),
            new UIPropertyMetadata(null, (b, _) => (b as ButtonBase)?.AddHandler(
                ButtonBase.ClickEvent,
                new RoutedEventHandler((bb, __) => GetTarget((ButtonBase)bb)?.Focus()))));
};

Usage is basically the same as above:

Note that the event can target/focus the originating button itself.