X.U.Hacks: Add "Stacking trays (trayer) above panels (xmobar)"

XMonad/Util/Hacks.hs

@@ -27,12 +27,17 @@ module XMonad.Util.Hacks (
   -- * Java Hack
   -- $java
   javaHack,
+
+  -- * Stacking trays (trayer) above panels (xmobar)
+  -- $raiseTrayer
+  trayerAboveXmobarEventHook,
+  trayAbovePanelEventHook,
   ) where
 
 
 import XMonad
 import Data.Monoid (All(All))
-import Control.Monad (when)
+import Control.Monad (when, filterM)
 import System.Posix.Env (putEnv)
 
 
@@ -93,3 +98,49 @@ javaHack conf = conf
   { startupHook = startupHook conf
                     *> io (putEnv "_JAVA_AWT_WM_NONREPARENTING=1")
   }
+
+
+-- $raiseTrayer
+-- Placing @trayer@ on top of @xmobar@ is somewhat tricky:
+--
+-- - they both should be lowered to the bottom of the stacking order to avoid
+--   overlapping fullscreen windows
+--
+-- - the tray needs to be stacked on top of the panel regardless of which
+--   happens to start first
+--
+-- 'trayerAboveXmobarEventHook' (and the more generic
+-- 'trayAbovePanelEventHook') is an event hook that ensures the latter:
+-- whenever the tray lowers itself to the bottom of the stack, it checks
+-- whether there are any panels above it and lowers these again.
+--
+-- To ensure the former, that is having both @trayer@ and @xmobar@ lower
+-- themselves, which is a necessary prerequisite for this event hook to
+-- trigger:
+--
+-- - set @lowerOnStart = True@ and @overrideRedirect = True@ in @~/.xmobarrc@
+-- - pass @-l@ to @trayer@
+--
+-- Usage:
+--
+-- > handleEventHook = … <> Hacks.trayerAboveXmobarEventHook
+
+-- | 'trayAbovePanelEventHook' for trayer/xmobar
+trayerAboveXmobarEventHook :: Event -> X All
+trayerAboveXmobarEventHook = trayAbovePanelEventHook (className =? "trayer") (appName =? "xmobar")
+
+-- | Whenever a tray window lowers itself to the bottom of the stack, look for
+-- any panels above it and lower these.
+trayAbovePanelEventHook
+  :: Query Bool -- ^ tray
+  -> Query Bool -- ^ panel
+  -> (Event -> X All) -- ^ event hook
+trayAbovePanelEventHook trayQ panelQ ConfigureEvent{ev_window = w, ev_above = a} | a == none = do
+  whenX (runQuery trayQ w) $ withDisplay $ \dpy -> do
+    rootw <- asks theRoot
+    (_, _, ws) <- io $ queryTree dpy rootw
+    let aboveTrayWs = dropWhile (w /=) ws
+    panelWs <- filterM (runQuery panelQ) aboveTrayWs
+    mapM_ (io . lowerWindow dpy) panelWs
+  mempty
+trayAbovePanelEventHook _ _ _ = mempty