Apple is pretty bad about making deprecations easy to comply with, since about 90% of the time they offer no replacement suggestion in the documentation (except for the most commonly used apis).
10.8 deprecates a slew of Quartz Display apis, including CGRegisterScreenRefreshCallback. Does anyone know what we're supposed to use now?
Apple says CGDisplayStream, not that there's any documentation to that effect (or any documentation for Display Stream, for that matter).