Finding out signals for an interface

[Andrei Zmievski <andrei gravitonic com>]

How can I find out the list of signals a certain interface type has 
given its GType? I tried using g_signal_list_ids(), but it just returns 
an empty array. I also tried using g_type_class_ref() to make sure that 
GTypeClass for the interface exists, but I get an error saying "cannot 
retrieve class for invalid (unclassed) type `GtkCellEditable''. Is 
there a way to retrieve a list of signals?

-Andrei