[Xmonad] darcs patch: Introduce NonEmptyStack.

Hi all, Here's a patch implementing a NonEmptyStack type that is our zipper without the Empty possibility. I like this change, but haven't cleaned up the comments as it's not clear that others will like it. I made modify accept a function that will only modify NonEmptyStacks, which covers all the possibilities but delete. Actually, I think I'll implement a clean:q Fri May 25 19:18:04 PDT 2007 David Roundy <droundy@darcs.net> * Introduce NonEmptyStack.