NSWindow in front of all applications + ignores spaces / fullscreen transitions

I'm working on a screen fading application to hide a strange transition to the entire OS X screen. In 10.7, I was able to do this by creating an NSWindow and using setCollectionBehavior to make it float over everything else:

[window setCollectionBehavior:NSWindowCollectionBehaviorStationary | NSWindowCollectionBehaviorCanJoinAllSpaces | NSWindowCollectionBehaviorFullScreenAuxiliary];

My application launches, disappears to black, and then waits for a signal from another application until it disappears and the content below it appears. However, in 10.8 it covers the screen, shows the moment of transition, when the application under it is full-screen, then appears before the application.

Any ideas on how to promote this app before these nasty transitions?