[Xmonad] darcs patch: set border color more judiciously, so layouts can cust...

This does much less resetting of border colors, but in my testing does enough. The result is that WindowNavigation can display which neighboring windows can be navigated to by giving them blue (or other) borders, which seems a bit handy. David Fri Sep 28 19:53:46 EDT 2007 David Roundy * set border color more judiciously, so layouts can customize this.