void GraphScrollerChangeInUndo(object sender, EventArgs e)
        {
            if (undoButton.IsEnabled != graphScroller.CanUndo())
            {
                undoButton.IsEnabled = graphScroller.CanUndo();
                undoButton.Content   = undoButton.IsEnabled ? undoImage : undoDisabledImage;
            }

            if (redoButton.IsEnabled != graphScroller.CanRedo())
            {
                redoButton.IsEnabled = graphScroller.CanRedo();
                redoButton.Content   = redoButton.IsEnabled ? redoImage : redoDisabledImage;
            }
        }