From what I can see there, that is a general windows overlay and not an intergration into Office, which would be much more ugly and afaik would not leak outside

From what I can see there, that is a general windows overlay and not an intergration into Office, which would be much more ugly and afaik would not leak outside the window. So I guess it goes a bit like: DB watch files, find pid of process editing them (PowerPoint w/e) and they overlay a window.