Hi! I have X11 code which looks something like the following. The problem is that TimerInterrupt gets sometimes thrown in a way that it kills the whole main thread. Probably it gets thrown in the middle of some nested function which unblocked exceptions. I found: http://hackage.haskell.org/trac/ghc/ticket/1036#comment:4 but this is not yet in GHC stable version. Is there some workaround for this? Because I have problems compiling current Haskell platform with GHC head. currentThread <- myThreadId _ <- forkIO $ timer currentThread block $ run display run display = do ... allocaXEvent $ \event -> do interrupted <- catch (unblock $ nextEvent' display event >> return False) (\(_ :: TimerInterrupt) -> return True) ... run display -- A version of nextEvent that does not block in foreign calls nextEvent' :: Display -> XEventPtr -> IO () nextEvent' d p = do pend <- pending d if pend /= 0 then nextEvent d p else do threadWaitRead (fromIntegral . connectionNumber $ d) nextEvent' d p data TimerInterrupt = TimerInterrupt deriving (Show, Typeable) instance Exception TimerInterrupt timer :: ThreadId -> IO () timer t = do threadDelay redrawInterval throwTo t TimerInterrupt timer t Mitar