Usage

As an extended example, consider the case where you want all of your docks (e.g., status bar) to "pop up" when you press the super key, and then vanish again once that keys is released.

Since docks are not generally part of XMonad's window-set—otherwise, we would have to manage them—we first need a way to access and manipulate all docks.

onAllDocks :: (Display -> Window -> IO ()) -> X ()
onAllDocks act = withDisplay \dpy -> do
  rootw <- asks theRoot
  (_, _, wins) <- io $ queryTree dpy rootw
  traverse_ (io . act dpy) =<< filterM (runQuery checkDock) wins

This is also the place where one could filter for just status bar, trayer, and so on.

Now we have to decide what kinds of keys we want to watch out for. Since you most likely use left super as your modifier key, this is a little bit more complicated than for other keys, as you will most likely see the key both as a KeyMask, as well as a KeySym. One could think a bit and probably come up with an elegant solution for this—or one could grab all possible key combinations by brute-force!

dockKeys :: X () -> [((KeyMask, KeySym), X ())]
dockKeys act = map (actKey . foldr1 (.|.)) . combinations $ keyMasks
 where
  actKey :: KeyMask -> ((KeyMask, KeySym), X ())
  actKey mask = ((mask, xK_Super_L), act)

  keyMasks :: [KeyMask]
  keyMasks = [ noModMask, shiftMask, lockMask, controlMask, mod1Mask, mod2Mask, mod3Mask, mod4Mask, mod5Mask ]

  -- Return all combinations of a sequence of values.
  combinations :: [a] -> [[a]]
  combinations xs = concat [combs i xs | i <- [1 .. length xs]]
   where
    combs 0 _      = [[]]
    combs _ []     = []
    combs n (x:xs) = map (x:) (combs (n-1) xs) <> combs n xs

Given some action, like lowering or raising the window, we generate all possible combinations of modifiers that may be pressed with the super key. This is a good time to say that this is just for demonstrative purposes, btw—please don't actually do this.

All that's left is to plug everything into the machinery of this module, and we're done!

import qualified Data.Map.Strict as Map

main :: IO ()
main = xmonad
     . … -- other combinators
     . useUpKeys (def { upKeys = Map.fromList $ dockKeys (onAllDocks lowerWindow) })
     $ myConfig `additionalKeys` dockKeys (onAllDocks raiseWindow)

myConfig = …