What is xfce4-screensaver?
xfce4-screensaver is a screen saver and locker that aims to have simple,
sane, secure defaults and be well integrated with the desktop.
xfce4-screensaver is a port of MATE Screensaver, itself a port of GNOME
Screensaver. It has been tightly integrated with the Xfce desktop,
utilizing Xfce libraries and the Xfconf configuration backend.