Ron Teitelbaum wrote:
> I saw that there was work on a call back structure for plug-ins, by any 
> chance has any of this work spilled over into FFI?

No. The main issue is that for a C callback you need to be able to "pop 
the arguments from the C stack" and there is no support for this yet.

> I would like to attach to a third party callback from FFI, is that possible?

Yes. You can write a plugin that takes the callback and signals a 
semaphore (or does other interesting things).

Cheers,
   - Andreas