I have a difficult question, that I have gone to extensive effort to answer for myself, and I had placed a (fairly high) bounty on it in the past which didn't result in any answer.
That was almost four months ago and I've just discovered some new info that narrows down the question quite a lot.
I edited my question, and would like to place another bounty. But it only allows a bounty of 500! That's a lot of rep for me, I think it's too much and perhaps the minimum bounty increase algorithm should be reconsidered.
The question is basically trying to find a workaround for what looks like an operating system or API bug in a fairly new feature of OS X.