Quoting Joachim Breitner
I would naively expect the last configuration to be [3][3] (focus on B) which is of course not possible. Or is it?
And it is not only about intuitiveness, but also very useful. When holding presentations, I tend to use a tool like pdf_presenter_console and therefore, my laptop screen (A) and the projector screen (B) display different workspaces. But when I then want to demonstrate something live, I?d like to have the same workspace on both.
This requires compositing, if I understand the state of the art correctly. You may also like X.L.IndependentScreens, the next best thing for two screens; it takes your list of workspaces and makes n copies of each (where n is the number of screens you have). You can then choose which workspace is showing on which screen independently (though of course, as above, you can't show a single window on multiple visible workspaces at once unless you want to hack some compositing support into xmonad). Cheers, ~d