Hello there!
I think it would be great if Railing had option to set it as zone boundary.
At this moment if we want to draw a zone for balcony/terrace or anything that is not in closed space we have option to either draw it manually or to draw line/polyline as a zone boundary and place zone after that.
But in many cases, railing is in some way used and in many cases is also defining the boundary of this space.