I looked at http://cocoadev.com/wiki/DontExposeMe searching for workaround
nothing really worked except.
self.window.level = kCGDesktopWindowLevel;
now maybe DETECT changes to expose and set that then 🙂 …
see How can one detect Mission Control or Command-Tab switcher superseding one’s program in OS X? for that 🙂
maybe an answer will come up there