Keep discover-overlay above other windows in XMonad

discover-overlay's windows are override-redirect, so XMonad doesn't
manage them and raising a floating window (e.g. a game) covers them.
Raise them again from the log hook after every change.

.config/xmonad/xmonad.hs

@@ -2,7 +2,7 @@
 
 import Data.Monoid
 import Graphics.X11.ExtraTypes.XF86
-import Control.Monad (liftM2)
+import Control.Monad (forM_, liftM2, when)
 import XMonad
 import XMonad.Actions.PhysicalScreens
 import XMonad.Hooks.EwmhDesktops
@@ -120,7 +120,8 @@ myConfig =
       layoutHook = myLayoutHook,
       startupHook = myStartupHook,
       manageHook = myManageHook,
-      handleEventHook = myHandleEventHook
+      handleEventHook = myHandleEventHook,
+      logHook = myLogHook
     }
     `additionalKeysP` [ ("M-b", sendMessage ToggleStruts),
                         ("M-S-l", spawn "slock"),
@@ -295,3 +296,17 @@ myHandleEventHook =
     <> Hacks.trayerAboveXmobarEventHook
     <> Hacks.trayerPaddingXmobarEventHook
     <> Hacks.fixSteamFlicker
+
+-- Log hook
+myLogHook :: X ()
+myLogHook = raiseDiscoverOverlay
+
+-- discover-overlay's windows are override-redirect, so xmonad doesn't manage them and
+-- raising a floating window (e.g. a game) covers them; put them back on top after every change
+raiseDiscoverOverlay :: X ()
+raiseDiscoverOverlay = withDisplay $ \d -> do
+  root <- asks theRoot
+  (_, _, ws) <- io $ queryTree d root
+  forM_ ws $ \w -> do
+    cls <- io $ getClassHint d w
+    when (resClass cls == "Discover-overlay") $ io $ raiseWindow d w