public class FocusManagerExtensions
{
	public static readonly DependencyProperty IsFocusedProperty = DependencyProperty.RegisterAttached("IsFocused", typeof(bool?), typeof(FocusManagerExtensions), new FrameworkPropertyMetadata(IsFocusedChanged));
	public static bool? GetIsFocused(DependencyObject element)
	{
		if (element == null) {
			throw new ArgumentNullException("element");
		}

		return (bool?)element.GetValue(IsFocusedProperty);
	}

	public static void SetIsFocused(DependencyObject element, bool? value)
	{
		if (element == null) {
			throw new ArgumentNullException("element");
		}

		element.SetValue(IsFocusedProperty, value);
	}

	private static void IsFocusedChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
	{
		object fe = (FrameworkElement)d;

		if (e.OldValue == null) {
			fe.GotFocus += FrameworkElement_GotFocus;
			fe.LostFocus += FrameworkElement_LostFocus;
		}

		if ((bool)e.NewValue) {
			fe.Focus();
		}
	}

	private static void FrameworkElement_GotFocus(object sender, RoutedEventArgs e)
	{
		((FrameworkElement)sender).SetValue(IsFocusedProperty, true);
	}

	private static void FrameworkElement_LostFocus(object sender, RoutedEventArgs e)
	{
		((FrameworkElement)sender).SetValue(IsFocusedProperty, false);
	}
}