Apple today seeded build 13D33 of OS X 10.9.3 to developers, just under a week after releasing the fourth OS X beta, build 13D28, and a month after the first 10.9.3 beta.
Apple continues to ask developers to focus on Graphics Drivers and Audio, and Safari. 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.