I have a stage that I am pushing into FullScreen Mode. After it enters fullscreen, I am clicking on a button which internally calls stage.visible = false on the FS stage. When that happens, the whole screen turns black and nothing can be done. I had to either remote login and kill the app or I had to restart the system.

I reproduced this on Mac 10.5 with jdk6 using JavaFX SDK b09, b10.

Not reproducible on Windows.
I have attached a sample test herewith.