Screensaver and screen lock formerly used in GNOME

 gnome-screensaver is a simple screen saver and screen lock, used in older
 versions of the GNOME desktop environment.
 .
 It is designed to support, among other things:
 .
  * the ability to lock down configuration settings
  * translation into other languages
  * user switching
 .
 This package is not necessary in the GNOME desktop environment, because
 GNOME Shell contains its own screen lock implementation. It can be
 used with alternative desktop environments.