Doing the setup after the `Plugin.call` is too late and leaves the tests failing. FWICT, the modal can get shown and dismissed before the code gets a chance to setup the `hidden` event handler. So we've gotta do it before making the call.
But we need to avoid setting up the handler if the showing of the modal gets cancelled, so we have to wait for `show` or `shown`.
IIRC, `shown` led to test failures, which leaves us with `show` as the event to wait for.