I'm having the exact same issue in 14w29a with OS X 10.9.2 on a MacBook Pro with a 2880x1800 Retina display and Java 6. I've been having it since 14w28a. It seems to be a issue handling Retina displays.
A workaround for this (until Mojang fixes it) may be to somehow get Java to run in Low Resolution mode, but haven't found a way to do that since it's not a native Mac application and so doesn't have the option under Get Info.
Valiec2019
I'm having the exact same issue in 14w29a with OS X 10.9.2 on a MacBook Pro with a 2880x1800 Retina display and Java 6. I've been having it since 14w28a. It seems to be a issue handling Retina displays.
A workaround for this (until Mojang fixes it) may be to somehow get Java to run in Low Resolution mode, but haven't found a way to do that since it's not a native Mac application and so doesn't have the option under Get Info.