For our (open source) fullscreen text editor we're changing background colors of gtk.Window, gtk.Fixed, etc. to custom colors. This works fine, but some GTK themes (e.g. Mac4Lin) define background pixmaps instead of background colors for some widgets. Those background pixmaps won't go away when calling modify_bg() methods of those widgets.
I know I can set pixmaps with bg_pixmap[NORMAL] = 'blabla.png' and that I can define my own gtkrc overrides with gtk.rc_parse_string(). But I don't know how to unset bg_pixmap[NORMAL].
So, how would I do that?