How to draw a notebook tab?

[George Petasis <petasisg yahoo gr>]

Hi all,

Can anyone help me in how to draw a notebook tab?
I am using Gtk to draw widgets for a non-Gtk application. I have made 
some progress (i.e.
here 
http://www.ellogon.org/~petasis/tcl/Images/ttkgtk3/TtkGtk3-Preview2.png 
and here 
http://www.ellogon.org/~petasis/tcl/Images/ttkgtk3/TtkGtk3-Preview3.png). However 
I am facing problems with the notebook tabs and spinbox.

I have looked into the notebook sources, and tried to copy how the 
notebook widget draws its tabs.
I can draw something that looks like a tab, but the upper part is always 
missing (I don't know why).
Can somebody explain how can I render a tab, using gtk_render_extension?

Regards,

George