ChatterBox.Client.Presentation.Shared.Behaviors.ReturnKeyCommandBehavior.OnCommandUpdatePropertyChanged C# (CSharp) Method

        private static void OnCommandUpdatePropertyChanged(DependencyObject dp, DependencyPropertyChangedEventArgs e)
        {
            var element = dp as UIElement;

            if (element == null)
            {
                return;
            }

            if (e.OldValue != null)
            {
                element.KeyDown -= HandleKeyDown;
                element.KeyUp -= HandleKeyUp;
            }

            if (e.NewValue != null)
            {
                element.KeyDown += HandleKeyDown;
                element.KeyUp += HandleKeyUp;
            }
        }