[Xmonad] darcs patch: ScreenLayouts.hs: updates to the last API changes

Hi, it took me sometime to understand what this short piece of code was trying to do, but after recording, unrecording, reverting and studing and so on and so forth, there we are. It should be working again. All that just to emulate a nice xinerama setup for those who cannot afford a real multihead setup... ciao andrea Tue Jul 3 18:42:09 CEST 2007 Andrea Rossato * ScreenLayouts.hs: updates to the last API changes A silent API change broke this nice piece of David's code: Spencer decided to move screen details into StackSet, and there we went to manipulate them!