Change the image of the shape being dragged somehow to indicate that it is the source. e.g. grayed or dotted outline, made invisible, etc. I wanted a second drag image to distinguish where a drop was allowed or not allowed. The drag cursor reflects that status, but I thought some other change to the actual drag image would be good. However, it looks like once a drag image is selected, it cannot be modified during that drag operation. If a drop fails, the dragged image just disappears. The original piece is still in place at the drag start location, but it would be cool to animate the movement of the drag image back to where it started.