Opaque Type?

[Kent <kenton wilson gmail com>]

Is GtkTextTag an opaque type or are you allowed to look at (and depend on)
its contents? Specifically, I was wondering if it is permissible to look at the 
'name' field or is it more correct to use a g_object_get() with the "name" 
property. If it is okay to look directly at 'name' in GtkTextTag then why does 
the "name" property exist? Is their an advantage to using g_object_get() rather 
than looking directly at GtkTexTag->name (other than eliminating the dependency 
on the 'name' field itself).

Thanks,
Kent