NSWindow with NSWindowCollectionBehaviorStationary is visible on the Dashboard. Is this a bug?
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