Comment 27 for bug 124315

Denny de la Haye, you seriously need to understand the technical details better before you can know whether it can be done or not.
The code in coment #14 requires that the application set WM_WINDOW_ROLE properly. If all applications did that, implementing this feature would be trivial.

The problem is that many (most) applications don't do this. In fact when quick testing a few applications I could not find ANY that did this. Which brings us back to what I said: This REQUIRES some application level support.

This doesn't mean this bug is invalid as such, because the window manager could provide one part of it. But it will not work without some application support.