This interesting tidbit from a post by Rainer Brockerhoff: "Well, Apple can certainly opt to tell people not to use certain APIs. In fact, on the Mac in the past, some large software publishers went ahead and used some of those "hidden" APIs anyway, with the result that Mac OS X still has to support lots of legacy calls that are broken, but can't even be properly fixed without breaking those applications!"
This is interesting, I have always thought that Apple exercised a higher degree of control with Mac OS X's APIs. Since it was Microsoft's lax control of use of undocumented API led to Window's tinkertoy structure. Then again, it was also said that Microsoft purposedly created those undocumented APIs for the advantage of its own applications.
