Fix unmap handling

According to the ICCCM, clients should send a synthetic unmap event when they
initiate an unmap.  The old code waited for these synthetic unmaps to unmanage
windows.  However, certain 'obsolete' clients do not send synthetic unmaps
(notably xpdf's find dialog).  These windows entered a zombified state: xmonad
does not manage them, yet they are still mapped and raised on screen.

The new algorithm (derived from wmii):
 - track windows that are mapped on screen
 - track the number of expected unmap events for each window, increment every
   time 'hide' is called on a window that is not mapped.
 - decrement the expected unmap counter on each unmap event
 - treat an unmap event as genuine (ie. unmap the window) when:
    - the event is synthetic (per ICCCM)
    - OR there are no expected unmap events for this window

darcs-hash:20070606214006-a5988-7c2eced85319ff506a9b7c9dc86d5946ca0da8e5

1 files changed, 19 insertions, 4 deletions

diff --git a/Operations.hs b/Operations.hs
index 707d210..bd85637 100644
--- a/Operations.hs
+++ b/Operations.hs
@@ -23,6 +23,7 @@ import Data.List            (genericIndex, intersectBy, partition)
 import Data.Bits            ((.|.), (.&.), complement)
 import Data.Ratio
 import qualified Data.Map as M
+import qualified Data.Set as S
 
 import Control.Monad.State
 import Control.Monad.Reader
@@ -66,7 +67,10 @@ manage w = withDisplay $ \d -> do
 -- should also unmap?
 --
 unmanage :: Window -> X ()
-unmanage w = setWMState w 0 {-withdrawn-} >> windows (W.sink w . W.delete w)
+unmanage w = do
+    setWMState w 0 {-withdrawn-}
+    windows (W.sink w . W.delete w)
+    modify (\s -> s {mapped = S.delete w (mapped s), waitingUnmap = M.delete w (waitingUnmap s)})
 
 -- | focus. focus window up or down. or swap various windows.
 focusUp, focusDown, swapUp, swapDown, swapMaster :: X ()
@@ -196,9 +200,15 @@ setWMState w v = withDisplay $ \dpy -> do
 
 -- | hide. Hide a window by unmapping it, and setting Iconified.
 hide :: Window -> X ()
-hide  w = withDisplay $ \d -> do
-    io $ unmapWindow d w
+hide w = whenX (gets (S.member w . mapped)) $ withDisplay $ \d -> do
+    io $ do selectInput d w (clientMask .&. complement structureNotifyMask)
+            unmapWindow d w
+            selectInput d w clientMask
     setWMState w 3 --iconic
+    -- this part is key: we increment the waitingUnmap counter to distinguish
+    -- between client and xmonad initiated unmaps.
+    modify (\s -> s { waitingUnmap = M.insertWith (+) w 1 (waitingUnmap s)
+                    , mapped       = S.delete w (mapped s) })
 
 -- | reveal. Show a window by mapping it and setting Normal
 -- this is harmless if the window was already visible
@@ -206,11 +216,16 @@ reveal :: Window -> X ()
 reveal w = withDisplay $ \d -> do
     setWMState w 1 --normal
     io $ mapWindow d w
+    modify (\s -> s { mapped = S.insert w (mapped s) })
+
+-- | The client events that xmonad is interested in
+clientMask :: EventMask
+clientMask = structureNotifyMask .|. enterWindowMask .|. propertyChangeMask
 
 -- | Set some properties when we initially gain control of a window
 setInitialProperties :: Window -> X ()
 setInitialProperties w = withDisplay $ \d -> io $ do
-    selectInput d w $ structureNotifyMask .|. enterWindowMask .|. propertyChangeMask
+    selectInput d w $ clientMask
     setWindowBorderWidth d w borderWidth
 
 -- | refresh. Render the currently visible workspaces, as determined by