I would like to stop gnome-session trying to launch an application each time I login, namely gnome-screensaver.desktop (since I have uninstalled in favor of xscreensaver so currently get a syslog error about not being able to find gnome-screensaver, of course because it was removed).

Is there somewhere that lists the applications gnome-session will try to launch that I can edit?

I thought it might be something to do with ~/.config/gnome-session or maybe /usr/share/gnome/autostart/, but I don't see any gnome-screensaver reference....maybe it can be changed with gsettings?

There should be an item somewhere in the menu called "startup applications" which allows you to add or remove items. They did remove it, but I think it's back again.

You mean Startup Applications in the top right (under System Settings etc)? If so gnome-screensaver is not in there. I think gnome-session is attempting to launch it somehow..

Finally, used `sudo find / -iname "gnome-screensaver.desktop"`, which showed me the presence of `gnome-screensaver.desktop` in `/etc/xdg/autostart/`, which was responsible for trying to load the uninstalled gnome-screensaver at each startup. Removing this file removed the error from syslog.