I really like using xscreensaver with electric sheep (getting increasingly old alas) with my computer. But !@#%$!@#% cinnamon won't let me change the screensaver. I tried systemd blah blah blah.
Easiest fix: just move cinnamon-screensaver to cinnamon-screensaver.old and symlink xscreensaver to cinnamon-screensaver. POOF voila happy xscreensaver again!
Thomas