Fix forking issues, add unix dependency.

README

@@ -15,6 +15,7 @@ Building:
 
     X11             http://hackage.haskell.org/cgi-bin/hackage-scripts/package/X11-1.2
     mtl             http://hackage.haskell.org/cgi-bin/hackage-scripts/package/mtl-1.0
+    unix            http://hackage.haskell.org/cgi-bin/hackage-scripts/package/unix-2.0 (included with ghc)
 
     X11-extras:     darcs get http://darcs.haskell.org/~sjanssen/X11-extras
 

XMonad.hs

@@ -24,7 +24,7 @@ import StackSet (StackSet)
 
 import Control.Monad.State
 import System.IO
-import System.Process (runCommand)
+import System.Posix.Process (newSession, executeFile)
 import Graphics.X11.Xlib
 import Control.Exception
 
@@ -73,8 +73,7 @@ io = liftIO
 
 -- | spawn. Launch an external application
 spawn :: String -> X ()
-spawn x = do v <- io $ handle (return . Just) (runCommand x >> return Nothing)
-             whenJust v $ \e -> trace $ "xmonad:spawn: unable to fork "++show x++": "++show e
+spawn x = io $ forkProcess (do newSession; executeFile "/bin/sh" False ["-c", x] Nothing)
 
 -- | Run a side effecting action with the current workspace. Like 'when' but
 whenJust :: Maybe a -> (a -> X ()) -> X ()

xmonad.cabal

@@ -7,7 +7,7 @@ license:        BSD3
 license-file:   LICENSE
 author:         Spencer Janssen
 maintainer:     sjanssen@cse.unl.edu
-build-depends:  base==2.0, X11>=1.1, X11-extras==0.0, mtl==1.0
+build-depends:  base==2.0, X11>=1.1, X11-extras==0.0, mtl==1.0, unix>=1.0
 
 executable:     xmonad
 main-is:        Main.hs