Flash Player 6.
someListener.onMouseUp
Listener; notified when the mouse is released. To use the onMouseUp listener, you must create a listener object. You can then define a function for onMouseUp and use the addListener method to register the listener with the Mouse object, as in the following code:
someListener = new Object();
someListener.onMouseUp = function () { ... };
Mouse.addListener(someListener);
Listeners enable different pieces of code to cooperate because multiple listeners can receive notification about a single event.