Gtk.mainGUI
--- | Copy the given surface to the exposed window on an expose event.
+-- | Called when (part of) the window should be redrawn. Copy the given surface
+-- to the exposed window on an expose event.
onExpose :: IORef Cairo.Surface -> EventM.EventM EventM.EExpose Bool
onExpose buffer = do
current_buffer <- liftIO $ readIORef buffer