void DoShowHighlight(double imageX, double imageY)
        {
            //If we were out of sync, and the first command
            //was a ShowHighlight, ignore it, since we don't
            //have an image yet.
            if (ImageControl.Source == null)
            {
                return;
            }

            var imagePos  = new Point(imageX * ImageControl.ActualWidth, imageY * ImageControl.ActualHeight);
            var canvasPos = ImageControl.TranslatePoint(imagePos, canvas);

            var h = new Controls.CircleHighlight();

            Canvas.SetLeft(h, canvasPos.X - h.Width / 2);
            Canvas.SetTop(h, canvasPos.Y - h.Height / 2);
            canvas.Children.Add(h);
        }
        void DoShowHighlight(double imageX, double imageY)
        {
            //If we were out of sync, and the first command
            //was a ShowHighlight, ignore it, since we don't
            //have an image yet.
            if (ImageControl.Source == null) return;

            var imagePos = new Point(imageX * ImageControl.ActualWidth, imageY * ImageControl.ActualHeight);
            var canvasPos = ImageControl.TranslatePoint(imagePos, canvas);

            var h = new Controls.CircleHighlight();
            Canvas.SetLeft(h, canvasPos.X - h.Width / 2);
            Canvas.SetTop(h, canvasPos.Y - h.Height / 2);
            canvas.Children.Add(h);
        }