It seems this is now moot, but meanwhile I asked the wx devs whether
these are undocumented public API or private helper methods, and it
seems worth relaying the reply - at least it will inform anyone
researching this issue who finds this thread:
<tierra> ojwb: that isn't intended to be a publically used
macro, though it is used to help define some public API methods
(tierra is Bryan Petty)
Cheers,
Olly