You can start the screensaver or lock the workstation instantly without the need of complex key/mouse inputs. Just place the mouse cursor at one of the corners of your desktop, say some magic words in your heart and your screensaver will be summoned immediately to your screen!
You can disable the screensaver at any time you want, for example, while watching movies/animations in window mode, playing games in window mode with a joypad, long-duration installation, up/downloading big files, burning disc.
It can also detect, in real-time, the state of the screensaver automatically, so that you could know whether the screensaver is active or has been temporarily disabled by some programs.