PyGTK and creating new widgets

[David Allen]

Hello,

I've been working with PyGTK recently, and so far, 
it's been quite easy due to the calling conventions
being so similar to C.

My question is, has anybody written their own 
widgets in Python for GTK, or is that generally 
done as a C module which then has to be 
incorporated into python as well?  In this case, 
I'm not talking about compound widgets such as 
something like a labeled entry, but a totally new
widget.  What I'm really looking for would be 
something along these lines - a tree layout, with
collapse-able subitems, but something that could 
also contain itself.  I know that CTrees can do 
something similar, but I want a bit more 
flexibility in terms of how the tree looks, (not 
just like a regular file tree) and also I don't
know that CTrees can contain themselves.  (I 
realize that items can contain subtrees, but I'm
talking about the *label* containing a subtree,
rather than having a subtree attached *underneath*
the label.

Does anyone know of any modules that might help,
or alternately, of any resources for writing 
custom GTK+ and GNOME widgets in python?

Any help would be appreciated.