private void OnGotFocus(object sender, RoutedEventArgs args)
        {
            _adorner = new ResizingAdorner(MyContent);
            _adorner.ResizeStarted   += OnResizeStarted;
            _adorner.ResizeCompleted += OnResizeCompleted;

            var adornerLayer = AdornerLayer.GetAdornerLayer(MyContent);

            if (adornerLayer != null)
            {
                adornerLayer.Add(_adorner);
            }
        }
        private void OnLostFocus(object sender, RoutedEventArgs args)
        {
            _adorner.ResizeStarted   -= OnResizeStarted;
            _adorner.ResizeCompleted -= OnResizeCompleted;

            var adornerLayer = AdornerLayer.GetAdornerLayer(MyContent);

            if (adornerLayer != null)
            {
                adornerLayer.Remove(_adorner);
                _adorner = null;
            }
        }