Custom event for "onReleaseOutside"

I’ve read about how to get an “onReleaseOutside” here:

Is there a way to extend the MouseEvent class to support this? In this way, the client class would only need to use:
addEventListener(MouseEventEx.RELEASE_OUT, onReleaseOutside).

I’ve got interface elements spread in my code that need to get onReleaseOutside and repeating the Senocular code in every place seems bad software engineering…

Thanks in advance.