Re: Better handling of window margins

[Eli Zaretskii]

> From: Yuri Khan <address@hidden>
> Date: Mon, 7 Dec 2015 16:35:06 +0600
> Cc: John Wiegley <address@hidden>, Stefan Monnier <address@hidden>, 
>       Emacs developers <address@hidden>
> 
> On Mon, Dec 7, 2015 at 9:32 AM, Eli Zaretskii <address@hidden> wrote:
> 
> > Can you name Emacs packages that implement those?  (The first item
> > excluded, of course.)
> 
> >> * Modification bars (which might display one marker on lines modified
> >> since the last save, another marker on lines which differ from the
> >> staged state, and yet another for differences from last commit)
> 
> [git-gutter.el by Syohei Yoshida]
> (https://github.com/syohex/emacs-git-gutter)
> 
> >> * “git blame” annotations
> 
> git-blame.el distributed with Git — currently emulates margins using overlays.

Thanks.  (But why do you say git-blame "emulates margins"?  It seems
like it uses line-prefix property entirely on purpose.)

These two fit well into the scheme I proposed.  Moreover, they both
display information that is per-line, i.e. not tied to any particular
buffer position, but to a whole line.  For such use cases, we already
have a way to control the order of display in the margin: the overlay
priority.  If all the packages put an overlay with a before-string
having the 'margin' display spec before the first character on the
line, then their stuff will be displayed in the order of the overlay
priorities.