Some of the old Unix GUI interfaces had a literal pin image on the corner of the top bar of each window. Clicking on it did exactly what you'd expect - pinned the window at this particular size/location and didn't let anything else overlap to cover it unless it was pinned that way. (they could "underlap" though).
Cease and Desists like this one and the current environment of DMCA-bombing always reinforce my belief that these corporate lawyers just need an excuse for staying on retainer.