From b948a50f8392202d03b19efac3eead7b8b19cd54 Mon Sep 17 00:00:00 2001
From: Spencer Janssen <sjanssen@cse.unl.edu>
Date: Thu, 7 Feb 2008 10:11:40 +0100
Subject: Remove non-existent windows on restart

darcs-hash:20080207091140-a5988-62b6074316ef87f2e728064f8262d9415ec9bee3
---
 XMonad/Main.hs | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/XMonad/Main.hs b/XMonad/Main.hs
index 0450a7c..7557ad6 100644
--- a/XMonad/Main.hs
+++ b/XMonad/Main.hs
@@ -16,6 +16,7 @@
 module XMonad.Main (xmonad) where
 
 import Data.Bits
+import Data.List ((\\))
 import qualified Data.Map as M
 import qualified Data.Set as S
 import Control.Monad.Reader
@@ -103,15 +104,17 @@ xmonad initxmc = do
 
             io $ sync dpy False
 
+            ws <- io $ scan dpy rootw
+
             -- bootstrap the windowset, Operations.windows will identify all
             -- the windows in winset as new and set initial properties for
-            -- those windows
-            windows (const winset)
+            -- those windows.  Remove all windows that are no longer top-level
+            -- children of the root, they may have disappeared since 
+            -- restarting.
+            windows . const . foldr W.delete winset $ W.allWindows winset \\ ws
 
-            -- scan for all top-level windows, add the unmanaged ones to the
-            -- windowset
-            ws <- io $ scan dpy rootw
-            mapM_ manage ws
+            -- manage the as-yet-unmanaged windows
+            mapM_ manage (ws \\ W.allWindows winset)
 
             -- main loop, for all you HOF/recursion fans out there.
             forever_ $ handle =<< io (nextEvent dpy e >> getEvent e)
-- 
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