Clone hook - segfault is bad, doc'd or not

Hello,

I was digging through the bugs and noticed the "segfault on clone" issue
was still there.  I've been thinking that we should just hook the clone
object handler and throw an exception/ fatal error - that way people
know that you can't clone gtk objects and we don't let the engine go boom.

Any opinions on the subject? (it'd fix the bug too ;)

Thanks,
Elizabeth