bug#8568: 24.0.50; fringe-indicator-alist doc

[Eli Zaretskii]

> From: "Drew Adams" <drew.adams@oracle.com>
> Date: Wed, 27 Apr 2011 13:31:14 -0700
> 
> 1. (elisp) Fringe Indicators: "`top-bottom" is missing the closing
> single-quote, for some reason: "...used only for the `bottom' and
> `top-bottom indicators when the...".

Yep, a missing quote.

> 2. There is no real explanation of LEFT1 and RIGHT1.  The pseudo
> explanation is unintelligible: "The LEFT1 or RIGHT1 bitmaps are used
> only for the `bottom' and `top-bottom' indicators when the last (only)
> line has no final newline."  That talks about the situation when they
> are used, but it doesn't explain what they are

This is supposed to be explained in the beginning of the section:

     Emacs can indicate the buffer boundaries--that is, the first and
     last line in the buffer--with angle icons when they appear on the
     screen.  In addition, Emacs can display an up-arrow in the fringe
     to show that there is text above the screen, and a down-arrow to
     show there is text below the screen.

Are the names of each of these all that's missing to fill in the
blanks?

> or how they are used.

This part I actually don't understand.  What do you mean "_how_ they
are used"? by drawing them in the fringes, of course!  What am I
missing?

> 3. This var maps logical indicators to bitmaps.  But we need to describe
> each logical indicator.  What does it mean?  When is it appropriate to
> use it?

Same answer as for #2, and the same text that's supposed to explain
that.

> But what about `overlay-arrow'?  Its description is "Overlay arrow
> indicator"  Well, duh, but what does that mean?   When do you use it?
> What is it intended for?

Type "i overlay-arrow RET" and you will see.  Will a cross-reference
there be enough?

> 4. The node ends with "Standard fringe bitmaps for indicators:" and a
> list of bitmap symbols.  A bitmap symbol such as `bottom-left-angle' is
> meaningless as just a name.  If we can't have images then at least
> provide one-line descriptions of what each looks like.

We _can_ have images, it's just a bit tedious to produce them.  As for
description... it's not easy.  Perhaps you could suggest the proper
descriptions, after looking at each one of the bitmaps.