When does Cocoa change nextKeyView

I'm trying to set up a reasonable tab order for VoiceOver/Full Keyboard access. I'm doing some of this with IB connections, and some with setNextKeyView: message.

I end up with something entirely different. I can can see that I end up with a different value for nextKeyView than what I set it to with setNextKeyView:, which I'm doing right after an addView:

So does anyone know when the system goes through and imposes its own order on things? When should I set up things how I want them?

David Dunham   www.pensee.com/dunham/
Imagination is more important than knowledge. -- Albert Einstein