who define *_parent_class variable ?

[KLEIN Stephane <stephane harobed org>]

Hello,

in many gobject source code I've some variable named 
"foo_bar_parent_class". Example in gedit source code :

* gedit_view_parent_class
* gedit_tab_parent_class
* gedit_statusbar_parent_class

I would like to know what is the macro definition that define this 
variable ? In gobject document, I found this : G_DEFINE_TYPE() [1] but 
this macro is never called in previous examples (gedit source code).

Someone can tell to me what define *_parent_class variable ?

Thanks for your help,
Stephane

[1] http://library.gnome.org/devel/gobject/2.6/gobject-Type-
Information.html#G-DEFINE-TYPE:CAPS