Bug report about the crash
https://bugzilla.gnome.org/show_bug.cgi?id=752775
Ok, another note:
The background changer is part of gnome-control-center.
Gnome control center requires that gdm is installed for the User
-account panel.
I wants this schema in particular /usr/share/glib
-2.0/schemas/org.gnome.login-screen.gschema.xml
So I still need gdm/gnome-shell installed.