Fraction input

[Nathan Hüsken <gtkmm lonely-star org>]

Hello together,
I want the user to be able to input a number as a fraction. So I would 
layout 2 sponboxes like this:

Spinbox1
--------
Spinbox2

The Problem is the line inbetween. It should be black! I tried with a 
label (playing around with glade), but the label always takes to musch 
space (or you can not see the black line).
What would be an easy way to make the black line?
Thanks!
Nathan