As expected, Apple has released OS X 10.10 Yosemite Developer Preview 4. It is available via the Mac App Store Software Update tab for developers running earlier versions of Yosemite. Apple has also released a revamped iTunes 12 to developers (full gallery here). Previous updates previously brought various design tweaks and feature enhancements, and Preview 4 is likely to do the same thing. Yosemite launches this fall with updated Mail, Messages, and Calendar apps, in addition to a system-wide redesign and improved integration with iOS Devices. We’ll be updating this post as new changes are discovered, and you can let us know what you find at

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-Redesigned Calculator app

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-Settings UI for dark mode tweaked

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– Improved ability to dial out any phone number via the FaceTime app