The clone method must be reconstructed in as3 custom events.

In the following example, the clone () method is the most important. You can use the clone () method to return a copy of the current event object. This clone () method generally does not need to be manually called. When we send an event object repeatedly, the eventdispatcher class will automatically call the clone () method to generate a copy of this event. Send the myevent event repeatedly. In a good understanding, the myevent event is forwarded. If the myevent event is not reconstructed, the clone method called by eventdispatcher is the event clone method during repeated sending, the cloned event is naturally an event class rather than a myevent. Therefore, when you use the E: myevent type to receive the event during listening, an error is reported and cannot be converted to the myevent class.