Actually it works fine. After you told me you use the middle button from dragging, everything seems to work well. Do you think that having arrow key support might be a good idea? It might be handy if I can use the arrow keys to, for example, drag a sprite from one spot to another without having to hold down the middle button, AND the left button at the same time. It would also be good for viewing the level, again, without the middle drag button.