[Xmonad] darcs patch: make DragPane work with the new Layout c... (and 3 more)

Here are a few more changes to DragPane. The compactification of code I could take or leave, but I'd definitely prefer to have the DragPane Nothing hidden from our users. They've got no need to know how we're implementing DragPane. Incidentally, I'd like to have the same change made in NewTabbed. David Wed Sep 26 15:04:39 EDT 2007 Andrea Rossato * make DragPane work with the new Layout class Wed Sep 26 15:09:00 EDT 2007 David Roundy * make DragPane a bit more succinct. Wed Sep 26 15:16:30 EDT 2007 David Roundy * hide implementation of DragPane from users. Wed Sep 26 15:16:56 EDT 2007 David Roundy * make DragPane code a bit more compact.