Advanced GB - possible to have image background?

Altering colours, fonts, etc is easy form the admin page, but I'm wondering if it's also possible for the GB to have a small tiling image for the background, not just a colour?

If so, could you please point out where I would change this - would I need to alter templates in some way?

Thanks!

Ha ha, belay that. I've just answered my own question: I just added background="whatever.jpg" in body of templates/header.php to see if that would do anything. Works fine.