Apple today seeded build 13D21 of OS X 10.9.3 to developers



From MacRumors:

Apple is currently asking developers to focus on Graphics Drivers and Audio. As was discovered with the first beta, 10.9.3 adds new support for 4K displays, offering "Retina" resolutions that improve readability along with support for 60Hz output from the Retina MacBook Pro. Apple has also released the new 11.1.6 iTunes beta to developers, which was initially seeded to Apple employees earlier this week.

  Apple Seeds OS X Mavericks 10.9.3 Build 13D21 to Developers