Gtk object system

[Piotr Zgórecki <piotr zgorecki wp pl>]

I'm trying to understand the Gtk 1.2 object system and one thing seems not quite clear to me.
Can one safely call a virtual method by making a simple public wrapper, that calls directly that method ?
As I'm wading through the docs I get the feeling that there are some reasons not to do this - and it should be done using signal emission. Why is that ? I can imagine no reasons, really ;) Or maybe I just get the wrong feeling. In other words, is marshalling always needed when calling a virtual method, or just when calling a callback ?
The second question that comes to my mind, concerning the same subject, is:
Why are the default signal handlers called using signal marshallers ? I understand the need for marshalling the user-registered callbacks, but the default handlers use the same calling convention as the functions that call them, don't they ?

Thanks,
Piotr

Oh, and I'm NOT sorry for my english. At least I can make a few people laugh :)