Hi, there's no config function called borderWidth. It's a field label of XState (so, exporting it from Config is going to conflict XMonad). So, shall we add it to config, and change its name? something like: initializeConfiguration = do -- -- Width of the window border in pixels -- modify $ \s -> s { borderWidth = defaultBorderWidth } defaultBorderWidth = 1 let me know. ciao andrea ps:I'm almost done with the contrib modules documentation