I am also interested in finding this program although I don't know if it will do what I want.
I need a program to make customizable copper "rainbows" on any screen. I know there are many programs on Aminet, but they are either AGA only (like Copper-Demon) or they only work on Workbench screen or they can't be customized. So far, the best I've found are "MrCopper" (for WB) and "rainbow" for other screens.
(Damn, this post made me go from "Merely Curious" to the far worse "Beginner"!)
