Increments the reference count for the interface type
and returns the default interface vtable for the type.
If the type is not currently in use, then the default vtable
for the type will be created and initialized by calling
the base interface init and default vtable init functions for
the type (the
class_init members of
g_type_default_interface_ref() is useful when you
want to make sure that signals and properties for an interface
have been installed.
vtable for the interface; call
|The data is owned by the called function.|