Our login screen requirements include a warning / disclaimer and a basic login, showing just a username and password field.  Sadly, Gnome 3 seems to be ignoring the org.gnome.login-screen.disable-user-list checkbox presented by dconf-editor.Can you disable the list of users displayed prior to login in Gnome 3 GDM?
How can I disable the user list login screen in Gnome 3 on Fedora 16 or 17?
fedora;login;gnome3;gdm