https://bugzilla.redhat.com/show_bug.cgi?id=997645
--- Comment #3 from Tom "spot" Callaway tcallawa@redhat.com --- If you're trying to set the text color in the button, this code works:
($button->get_children)[0]->modify_fg(normal => Gtk2::Gdk::Color->new(0xffff, 0, 0));
If you're trying to set the background color in the button, man... I don't know if that's ever worked right. I think Gtk3 uses CSS to do that reliably.
You might try opening this bug with the perl-Gtk2 upstream.