Gtkmozembed multiple processes

I am trying to use a gtkmozembed widget in more than one process, but I
get
a Segmentation Fault when I try and start the second running. I have
tried
defining separate set_profile_path’s for each process, to no avail.
However,
I am able to successfully use more than one widget within the same
process.

Is this a bug?

Many thanks,

Andy.