I tracked down that fullscreen bug in Leopard. The problem is that apparently you're not supposed to re-parent NSOpenGLViews. Either use an NSView subclass with it's own NSOpenGLContext or release and recreate the view every time you switch between fullscreen and windowed.

See this email for more info:
http://lists.apple.com/archives/Mac-opengl/2002/Feb/msg00180.html

I tried to change the XeeView to an NSView subclass but I still couldn't get it to work even following the instructions in the email. I'm guessing it's a bug in Leopard since it worked just fine in Tiger. Judging by the date of the email, I'm guessing they counted re-parenting as a bug and fixed it in Tiger and just re-broke it in Leopard.

I was able to get it to work by destroying and recreating the view each time though. Things didn't work perfectly but I suspect that's a combination of me not understanding your code very well and me still trying to get the hang of the new XCode tools.