For those who prefer messes, there's now a program that turns the PC desktop into the equivalent of the paper-strewn office. Abandoning ­folders ­within folders, the new approach, called BumpTop, uses paperlike icons that can be scattered, stacked, or stuck to virtual walls. The brainchild of Anand Agarawala, a former computer science graduate student at the University of Toronto, BumpTop borrows animation techniques from video-game development, and the icons move as if they were subject to real gravity, momentum, and friction. "The 'PC desktop' was supposed to be a meta­phor for managing our files," says ­Agarawala. "But my real desk looks nothing like my desktop." He has cofounded a startup in Toronto to commercialize his technology.