I'm also adding a separate comment as a bonus, because this may open yet some other cans of worms and I want to keep it separate from the original one, so please bear with me: As for the universal/document layers themselves, and their visual manifestation in the Studio UI, any layer sitting above the topmost artboard could automatically become “universal”… because it technically already is. That is intuitive for any user to grasp, but some extra visual feedback – like, say, change its descr