bug#47835: Wishlist: New footer line immediately above the mode line

[Eli Zaretskii <eliz@gnu.org>]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: 47835@debbugs.gnu.org, "'Eli Zaretskii'" <eliz@gnu.org>
> Date: Wed, 29 Jun 2022 13:12:29 +0200
> 
> Stefan Kangas <stefan@marxist.se> writes:
> 
> > It would be useful to have a footer line that would work like the header
> > line but was at the bottom instead, immediately above the mode line.
> 
> Yes, I can see that being very useful in some modes.
> 
> I have no idea whether it would be much work to implement -- Eli, could
> we reuse the header line code for something like this (but just, er,
> "move it down" 😀), do you think?  (I haven't looked at it at all.)

It's possible (in fact, addition of tab-line did just that, more or
less).  But to have a special screen line at bottom would be a more
complex job than what was done for tab-line, IMO, because its position
relative to the window's top should change whenever the window
dimensions change.  So the display code and the code which handles
window dimensions will have to be taught about such a special line.
Not rocket science, just a lot of boring bookkeeping...

Volunteers are welcome (and will be helped if needed).