This is new for me. One of the most “unnecessary” things in SL is showing the classic –and dreadful– ban lines to the world. They don’t stop people from spying on you as disabling the “Avatars on other parcels can see and chat with avatars on this parcel” option does, and from my point of view they only “depreciates” your property, aesthetically speaking. Yet, some residents are fond of them and recur to their use on a regular basis (some can’t live without them, it seems to me sometimes).
Not this neighbor, though. Apparently she wanted to enable ban lines selectively on one side of her parcel only, but since there’s no such option in SL, she opted to erect an equivalent: let’s call it a personalized ban line screen… I won’t speculate on why this 8 and a half year-old resident would do this, but mind you passive-aggressiveness comes to mind.