found a way to set screensaver in gnome 3
$ sudo yum remove gnome-screensaver
the above command also remove gnome-screensaver-command, which is called when press Ctrl+Alt+L to lock the screen
$ sudo yum install xscreensaver
now select your favorite screen-saver, but what about locking system? For that do following:
$ su -
# cd /usr/local/bin
# vim gnome-screensaver-command
#!/bin/bash
xscreensaver-command -lock
save & quit
# chmod +x gnome-screensaver-command
voila, now you can lock your system by pressing Ctrl+Alt+L, ie same gnome keyboard shortcut
Linear Mode
