> So it might seem too early to document them in the Emacs manual.
I think the main reason why they're unused is that they're
completely undocumented. I'd love to see some rough documentation for it.
It will hopefully help us all better understand the feature and improve it
(especially the UI part).
I think even a somewhat incorrect documentation would be a good thing
because it would hopefully give us bug-reports that'll help us improve both
the code and the doc.