bug#35737: xref--original-command

[Juri Linkov]

> But please wait a little, I'd like to show a patch for bug#35702 that can
> also provide a basic for the same distinction in functionality but without
> this variable.

OK.

>> Emacs has side windows too.
>
> You mean like Speedbar? That's the part which I didn't exactly like.

I don't like Speedbar too because it's too intrusive.  But maybe
it can be rewritten using real side windows as documented in
(info "(elisp) Side Windows")