bug#11832: 24.1.50; enhancement request: line truncation not dependent on fringe

[Drew Adams]

Prior to Emacs 21, truncated lines are indicated by an overlay with a
`$' symbol shown on each line at the right window edge, i.e., within the
window & buffer - not in the fringe.
 
This is a reasonable indication of whether a given line is truncated.
 
In Emacs 21+, this representation was lost AFAIK, replaced by adding a
symbol to the right fringe.  That representation is reasonable ONLY when
a user chooses to show the right fringe.  Otherwise, it is useless: it
does not tell you which lines are truncated.
 
Please let users choose the representation to use.  One way to do this
would be to let option `truncate-lines' respect different non-nil
values, e.g. `right-fringe', `overlay'.
 
Since the fringe representation is not general (is useless unless fringe
is shown), the default should be the pre-Emacs 21 behavior of using an
overlay.  But I won't argue about the default.  Please provide users a
way to get the pre-21 behavior - that's the main point.
 
A third distinguised non-nil value, `fringe-if-shown', could use the
right fringe if it is shown and an overlay if not.  That too would be a
reasonable default value.  It could in fact be the behavior for an
undistinguished non-nil value, i.e., any value other than `right-fringe'
and `overlay'.

In GNU Emacs 24.1.50.1 (i386-mingw-nt5.1.2600)
 of 2012-06-18 on MARVIN
Bzr revision: 108646 michael.albinus@gmx.de-20120617185439-jfcgwwbr97nbflkz
Windowing system distributor `Microsoft Corp.', version 5.1.2600
Configured using:
 `configure --with-gcc (4.6) --no-opt --enable-checking --cflags
 -ID:/devel/emacs/libs/libXpm-3.5.8/include
 -ID:/devel/emacs/libs/libXpm-3.5.8/src
 -ID:/devel/emacs/libs/libpng-dev_1.4.3-1/include
 -ID:/devel/emacs/libs/zlib-dev_1.2.5-2/include
 -ID:/devel/emacs/libs/giflib-4.1.4-1/include
 -ID:/devel/emacs/libs/jpeg-6b-4/include
 -ID:/devel/emacs/libs/tiff-3.8.2-1/include
 -ID:/devel/emacs/libs/gnutls-3.0.9/include
 -ID:/devel/emacs/libs/libiconv-1.13.1-1-dev/include
 -ID:/devel/emacs/libs/libxml2-2.7.8/include/libxml2'