Hi again. The first patch removes (unused there) datatype declaration from X.L.LayoutBuilderP module, and exports Predicate typeclass from it. instance Predicate p w declaration means that "p" type may be used as (monadic) predicate on "w" type. Obvious example is instance Predicate Property Window. Other examples could represent some predicates on window groups or smth else. The second patch is for xmonad-extras repository. It adds new module, XMonad.Util.WindowPropertiesRE. PropertyRE is almost same as X.U.WindowProperties.Property, but while Property needs exact string (title/window class/whatever) matching, PropertyRE uses regular expressions matching. For example, Title "#xmonad" matches only windows having exactly "#xmonad" in title, but RE (Title "xmonad") matches windows with titles "xmonad@conference.jabber.ru" and "#xmonad" and so on. Also X.U.WindowPropertiesRE module contains instance declaration for Predicate PropertyRE Window. To use regular expression, I added build-depend from "regex-posix" package into xmonad-extras.cabal. WBR, Ilya Portnov.