AS3 Gestures is a library for defining event-based Gestures, and Behaviors to respond to Gestures.

A Gesture is a collection filtered events. A gesture can listen for as many types of events as it requires, but it only fires when the events occur in a specific order.

When a Gesture is activated, it can respond to any number of Behavior objects. Behaviors implement IBehavior, and will receive a list of the Events that in the order they activated the Gesture.

Example:
"ABCGesture" listens to events A, B, and C, so ABCGesture will be notified every time events A, B, and C are dispatched. But ABCGesture will only activate if the events occur in order A-B-C. When that happens, ABCGesture will fire to each behavior attached to it.

In this example, it can be said that state B has a dependency on event A occuring, and C has a dependency on the A-B sequence. This can be modeled thusly:
<A>
  <B>
    <C/>
  </B>
</A>
where <a/> is the root node in a hierarchical state machine.

ABCGesture may receive an event stream like this: A-C-B-A-[A-B-C]-C-A-B-B. The events outlined in brackets are the sequence that trigger the gesture to fire, and they are passed to each Behavior as a list.