[HOpenGL] Exiting gracefully from (H)GLUT?

Hello. I have recently started using the HOpenGL (version 1.01) under Linux running ghc 5.02.1 and have a question. How do I exit my application gracefully (apart from closing the window). In your examples you use

exitWith ExitSuccess

That however causes a: TestGLUT: fatal error: GLUT_CBWindow_d7Tf: uncaught exception Similar error appear in my application. How do I get around this? It does not appear to help to do a destroyWindow before exiting. Any ideas? Thanks, Calle