Coming back to this before I finally sleep.

I missed your point about selector matching and style application. I think that is ultimately where my hip shot missed on this. (I have never had to reserve the right to be wrong. Just to assume it. :)

I still feel there is some danger there, but I think that is just clinging to an initial shot. I am curious why rust's help was needed to get this, now. A basic thread pool seems like it would have been somewhat easy to wire up in any language.