The #9front rio right click menu shows labels of windows that have been explicitly hidden to bring them back up. But how awesome is that it also shows labels for windows that are not hidden, but simply obscured by other windows at the moment.
What a good design.
ANSI art in vt(1). Doing better job than most modern terminal emulators. #9front
"I appreciate SDF but it's a general-purpose server and the name doesn't make it obvious that it's about art." - Eugen Rochko