Apple today seeded build 13D28 of OS X 10.9.3 to developers, a little over one week after releasing the third OS X 10.9.3 beta, build 13D21 and three weeks after the first 10.9.3 beta. The beta is available through the Software Update mechanism in the Mac App Store as well as through the Mac Dev Center. 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.
