|Following the release of internal betas distributed to Apple and AppleCare employees on Tuesday, the company has now made its latest betas for OS X Mavericks and iTunes available to developers. As noted previously, the update to iTunes restores local management of Contacts and Calendar data for users who prefer not to use iCloud syncing. The latest Mavericks beta features improved support for 4K high-definition displays.
The 4K support, spotted in the previous developer beta of 10.9.3, introduces both a new pixel-doubled "Retina-quality" scaling option as well as bumping up the refresh rate from the previous 24Hz (at 4096x2160) to 60Hz even at that maximum resolution, making animation or fast action smoother. The change will mostly benefit owners of Retina MacBook Pros who connect to 4K displays over HDMI.
Apple is asking developers to focus testing on graphics drivers and audio features, such as the recently-introduced FaceTime audio calling. Also listed as an area of testing is Safari, which recently saw its own beta release.
The iTunes 11.1.6 beta allows those with sensitive contact or calendar information that don't want to sync to remote servers or transmit the data (even securely) over the Internet to use local syncing instead. The feature had been a part of iTunes previously, but was removed without explanation in the previous iTunes release. Both betas are now available from Apple's developer website or through Software Update for registered developer accounts.