Re: Line Numbering -- remove leading space; and, customize trailing character.

[Eli Zaretskii <eliz@gnu.org>]

> From: Keith David Bershatsky <esq@lawlist.com>
> Date: Thu, 22 Aug 2019 18:53:58 -0700
> 
> All of that got me thinking ... how would it look if I removed the leading space and changed the trailing space into a "|" symbol?  Attached is a screenshot of what this looks like ...
> 
> Have there been some requests to customize the leading/trailing spaces, and, if so, what was the consensus?  If not, then it may be something worth considering ....  I think the attached screenshot looks kind of nifty, and saves me 11 pixels of screen real estate after eliminating one character (the space) on the left, which happens to be my frame-char-width ...

The leading space that looks "useless" to you makes the display of
line numbers in R2L text as efficient as in L2R text, for somewhat
complicated technical reasons (I can explain if someone _really_ wants
to know, but believe me: you don't ;-).  I bet people who wonder about
those "wasted" few pixels never use R2L or bidirectional text, but we
cannot do anything in Emacs these days on such assumptions.

So yes, this single space is there to stay, at least for now.  The
only compromise we could perhaps consider is replacing the ASCII space
with a thinner non-ASCII space character (on both sides of the
number), although this would get us into the mess of how to detect if
the face's font has a glyph for that, and what to do if it doesn't.
Which is already an expensive complication.

Bottom line: with today's wide hi-res screens, I really cannot
understand why half a dozen pixels "wasted" on that space could make a
difference important enough to complicate the heck out of this
feature.