Thanks to Chris Anderson for his reply.
I have now found and fixed the problem, which was a pig because I didn't
know where to start looking, and I was no longer familiar with my own
code. The faults resulted from signal handlers being installed for
'focus-in-event', in the case of the GtkEnt
At first, I would suspect that the use of deprecated widgets could
cause this problem. As it turns out, GtkClist is indeed deprecated
(use GtkTreeView instead). However, GtkEntry is not deprecated, so I
am surprised that it too doesn't work properly. I would go through the
GTK 2.x documentation and
