Late yesterday, Apple seeded the first beta of OS X 10.9.3 to Mac developers. The beta seemed insignificant, with no mention of any changes or new features; just a brief request that devs focus their testing on audio and graphics.
But as it turns out, there is at least one notable difference in the beta: a new 'Native' Retina resolution option for 4K displays. This enables users with compatible displays to use OS X in a noticeably sharper Retina mode at 60Hz...