Implement HiddenNonEmptyWS with HiddenWS and NonEmptyWS
Implement HiddenNonEmptyWS with HiddenWS and NonEmptyWS

(Just to reduce code duplication)

darcs-hash:20081006211027-23c07-c89e895fb241d5c289348c3f35019edf9d56e380

jthornber/XMonadContrib,jthornber/XMonadContrib