I dont really know, what timer functions there are, I googled "timing, scheduling, delaying in haskell", but the only function I found, was threaddelay. How did you mean "adding a timer"?
On the other side, I checked Graphics.UI.Gtk.Gdk.drawWindowProcessUpdates. I guess, I
It may not actually be the right function. Felipe was however correct in that it's the wrong way to go about it; see the above to add a callback that executes after a delay, *without locking up the UI* which is what the threadDelay method will do.