>
> Not a vital thing, but why "failed" here? If a selection is made and
cleared, success and failure seem unusual choices for event names. To me
it's closer to "focus" and "blur", or "selection" and "deselection".

IIRC, there are situations when the user actively selects something, but we
realize that it's all part of annotator ui, so we don't bring up the adder.
That's what is called a failed selection here.

We handle this by hiding the adder, but I don't think the semantics is the
same as deselection.

I'll take another look when I have a chance.