"Use gestures"

I began using a simple word-processing program for Mac called “Writer.” In its “Preferences” you can choose “Use gestures,” but I cannot understand what it means. Is there anyone who can tell me what it is for?
http://bit.ly/k9BE3C

On an iPad, you can drag your fingers across the screen to perform certain functions. I don’t think your screen is tactile, but perhaps you can use these gestures on the mouse pad?

Thank you, Alexandrec.
I put two fingers on the mouse pad, and widened the distance between them. Suddenly the window of the program became extended into a full-screen mode.