Ok, so in Machintosh OSX Maverick 10.9.x there is now added fullscreen apps funtionality, being that you can make an app fullscreen on one monitor while still being able to fully utilize the second/thrid monitor(s), the glitch is that when minecraft is put into fullscreen on either monitor, it will not only only go to the monitor that has the dock on it, but it will also black out all other monitors rendering them useless..
_
How to:
Go fullscreen on any version of osx mavericks.