In this code:
> this.thing.onAction.add(this.onAction, this);
this.thing.onAction is an event source while this.onAction is a listener.
It's confusing having the same naming standard for both. We should have:
> this.thing.onAction.add(this.actioned, this);
So this.thing.onAction is an event source while this.actioned is a listener.
Fixed with the closing of bug 720641