xstroke is a full-screen gesture recognition program written for the X
Window System. It captures gestures that are performed with a pointer
device, (such as a mouse, a stylus, or a pen/tablet), recognizes the
gestures and performs actions based on the gestures.

xstroke is most commonly configured to "type" characters in response to
gestures, but it can also emulate mouse button "clicks", launch programs,
and other fun things.