IMHO Mac OS forwards/backwards compatibility is truly pitiful. Makes me almost want to not develop things for the MAC platform. Backwards compatibility on Windows is solid. Things that run on Vista run on Windows 7 run on Windows 8, because the core windows dll’s and functions hardly ever change and there isn’t much depreciation, whereas Mac OS X is always a can of worms. Even though I just develop simple plugins, you never quite know what parts of the Cocoa Framework are going to become depreciated (for example). Very frustrating. I wouldn’t really blame developers, I’d blame apple for needlessly changing things around on EVERY UPDATE to OS X and making developers scramble to figure out what subtle little changes have occurred.