Re: relative line numbers and folding: how to make they play along?

[Eli Zaretskii <eliz@gnu.org>]

> From: Filipe Silva <filipe.silva@gmail.com>
> Date: Wed, 13 Jul 2016 19:33:34 -0300
> Cc: help-gnu-emacs@gnu.org
> 
> Eli, sorry, I did not answer your question because everybody on other forums, github, etc... told me that I
> would need to install a third party package to do what I showed and even them, it would not play along with
> folding. 
> 
> So I wanted to know if you could, starting from emacs -Q, construct a lisp code that achieved the effect
> shown here:
> 
> https://cloud.githubusercontent.com/assets/8352747/16707876/4bd64c22-45b5-11e6-8d13-ae9c994cbb02.png

Problem is, I don't really understand what's the desired effect shown
there, exactly.  That's why I asked to explain what do you mean by
"relative line numbers".  Does that mean "count lines that will be
displayed, skipping the invisible ones"?  Or does it mean "count lines
shown in a window, where the first visible line in the window is
always line 1"?  Or does it mean something else?

> If it can't be done, I think it is the case to issue a feature request for that. 

A feature request will have to describe the desired feature, so what
I'm asking is needed for that as well.

Thanks.