Your reward is that personal inner glow, and the chance to bring your friends and family around to see ... ... on the other hand, maybe I should add something that will bring the crowds in without your intervention. :)

mjrb4: Thanks for the positive feedback. Greenfoot made this really easy to program. A Solve button is a nice idea but I will probably leave that to others. (On the other hand, there are some things it is hard to resit!

I will see what I can do about the jerkiness. You don't have to put the mouse on the board, it works anywhere on the world, just measuring the offset from the initial press to the current position.