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; } }