The Gesture trigger (v8+) lets you execute a macro when you draw a shape using the mouse.
The gesture consists of any sequence of one or more directional movements (horizontally, vertically, or diagonally). The gesture can require a set of modifiers to be pressed, or a specific mouse button to be pressed, and you can optionally make the gesture reversible (so, for example, up, right, up, left would also trigger if you drew the shape in the reverse direction right, down, left, down).
You can practice gestures by choosing Practice Gestures from the Help menu