OS X and Mac OS X 10.0-10.6 _ARE_ open source. Most services (including Quartz, the display server) are not. macOS could be once there is a new code drop, if th

OS X and Mac OS X 10.0-10.6 _ARE_ open source. Most services (including Quartz, the display server) are not. macOS could be once there is a new code drop, if they ever bother.