I'm running Gnome 3.8.1 with Ubuntu 13.04 via the GNOME3 PPA. Per Adam's notes, I've been able to workaround this problem by using the Adwaita GTK theme rather than Ambiance.
I can also confirm that Radiance reproduces the same wallpaper behavior.
I'm running Gnome 3.8.1 with Ubuntu 13.04 via the GNOME3 PPA. Per Adam's notes, I've been able to workaround this problem by using the Adwaita GTK theme rather than Ambiance.
I can also confirm that Radiance reproduces the same wallpaper behavior.