Change the font of a button

["Diego A. Fons" <diegofons apexar com ar>]

Hi,

I'm trying to change the font and color of a button and add an image to 
the button but i'm having troubles.
In a regular button (without an image) i can change the font by getting 
the child (which is a Label) and modify the properties of that label.
The problem is when i put an image into the button 
(Gtk::Button::set_image()), after doing that the font is set to the 
default values.

Is this behavior correct or it's a kind of bug?
How can i change the font properties of a button when it has an image?

Regards,
Diego A. Fons.