The basic problem I have with this is that it just finds the first ComboBox in the *dom*, not necessarily the first one the user sees. Could be invisible (not totally sure of this) could be on the main page (i.e. when the user is in a modal window - technically the one on the main page will come first), or they could be reordered on the page.

Helpful for testing individual components, but less good for describing the relationship of the elements in a full application.

If we were to go this route, I'd want to make it configurable globally, and off by default, to avoid possible confusion. Or, since the point here is to just find the first thing that matches, a `GwtWidget.findFirst(Class<T extends GwtWidget)` that returns `T` rather than a `finder<T>`. That could key off of `@ForWidget` and find the first (visible?) instance in the dom.