Detecting the number of aux buffers is trivial and can be done using the fake GL context as it is a WGL pixel format property.
Not quite: What if a card supports AUX buffers with the R5G6B5 equivalent, but not with A8R8G8B8? Of course I could try to create the fake format with aux buffers enabled, but who tells me if the number of aux buffers is going to work with the format the application wants later?
As I said before aux buffers are a WGL pixel format property. The pixel format selection code needs to take care of it. Right now it already tries to locate a format with aux buffers but it isn't failproof yet (wglChoosePixelFormatARB searches for an exact match or else for something with better capabilities; this is a little too strict for us) I'm working on better pixel format selection code but my time is very limited right now.
Roderick