Jan Vroonhof <vroonhof(a)math.ethz.ch> writes:
1. It is not documented
2. 2 out of 3 official ways are doing it are broken (basically
because these parts of the Xt and Motif libraries weren't used
much).
Both points really boil down to the need of someone shaking the dust
off it. We've discussed this at the symposium, and the general
conclusion was that nobody knows how external widget support really
works.