preventDefault() not working on DragEvent

Getting a runtime error:
TypeError: Cannot read property 'preventDefault' of null (null is the event object)

This could be because

COMPILE::JS
public class DragEventBase extends goog.events.BrowserEvent

While the controller creates the event and dispatches it on a Royale element. In other words there's no related browser event that's kept in reference.

@aharui ,
Is there a reason DragEventBase does not extends org.apache.royale.events.Event ?

Start with DragEventBase and its COMPILE::JS declaration, then trace the controller path that creates and dispatches the event on a Royale element. Reproduce the preventDefault() failure and inspect how the event object is retained; done means DragEvent preventDefault() no longer encounters a null event reference.

Written by the indexing model from the issue text.