Don't know about the shrouds, most just run a small flag halyard to the underside of the spreaders. If it attached to the shrouds, it would be permanently up. You will want to be able to lower and remove them for different reasons ; UV proterction, Heavy wind, etc., and like Boasun said: communicate your intentions; is it cocktail hour or are we going fishing?
Courtney is My Hero
If a man is to be obsessed by something, I suppose a boat is as good as anything, perhaps a bit better than most - E.B. White