Is it possible to detect Keyboard focus events globally?

Question

The following events can be used, but, they must be attach for each element:

GotKeyboardFocus, LostKeyboardFocus

Is there a way in .NET WPF to globally detect if

Answer 1

Have a look at how Microsoft trigger CommandManager.RequerySuggested event when focus changes: they subscribe to InputManager.PostProcessInput event.

ReferenceSource

Simple example:

static KeyboardControl()
{
    InputManager.Current.PostProcessInput += InputManager_PostProcessInput;
}

static void InputManager_PostProcessInput(object sender, ProcessInputEventArgs e)
{
    if (e.StagingItem.Input.RoutedEvent == Keyboard.GotKeyboardFocusEvent ||
        e.StagingItem.Input.RoutedEvent == Keyboard.LostKeyboardFocusEvent)
    {
        KeyboardFocusChangedEventArgs focusArgs = (KeyboardFocusChangedEventArgs)e.StagingItem.Input;
        KeyboardControl.IsOpen = focusArgs.NewFocus is TextBoxBase;
    }
}

This also works in multi-window applications.