Eliot,

I am calling something that I *think* simply tells GSL where to find the callbacks and a relevant structure.  But I am getting a primitive failure in VMCallbackContext32>>primReturnAs:fromContext:, which I assume means that the library is attempting to call into Pharo.

In the debugger's context, ec is set to #'bad number of arguments'.  I have looked at the signatures and the blocks, and the argument counts look correct at first glance, albeit toward the end of a long day.

Am I being naive?  Any better ideas?  My next inclination is to set breakpoints in all of the callbacks to seee if any of them get hit.  I can't see why they would, but it's possible - especially given other weirdness that I have observed in GSL.  It work, but it's a little rough around the (design/elegance) edges at times.

Bill