GtkNotebook bevel border

[Paul Wellner Bou <paul purecodes org>]

Hello,

I am trying to get rid of the bevel border of GtkNotebook with tabs 
enabled in any way. I read in the documentation that unsetting 
show_border "...only has a visual effect when the tabs are not shown".

Is there any workaround/hack to change the border appearance of the 
GtkNotebook anyhow?

(I searched for styles of GtkNotebook and GtkWidget to modify, too, but 
I didn't found an apropiate value.)

Thank you and regards
Paul.