Added fill-column-indicator manual documentation

*etc/NEWS: reduced the comments about fill-column-indicator
*doc/emacs/display.texi: Added documentation for fill-column-indicator
 in this section in the manual

1 files changed, 45 insertions, 0 deletions

diff --git a/doc/emacs/display.texi b/doc/emacs/display.texi
index f464a3a59f0..62a4b62cfca 100644
--- a/doc/emacs/display.texi
+++ b/doc/emacs/display.texi
@@ -1141,6 +1141,51 @@ right-to-left paragraphs.
 @node Displaying Boundaries
 @section Displaying Boundaries
 
+@cindex mode, fill-column-indicator
+@findex display-fill-column-indicator-mode
+@findex global-display-fill-column-indicator-mode
+  Emacs can add an indicator to display a fill column position. The
+fill column indicator is a useful functionality specially in
+prog-mode to indicate the position of an specific column.
+
+  You can set the buffer-local variables @code{display-fill-column-indicator} 
+and @code{display-fill-column-indicator-character} to activate the
+indicator and controls how the indicator looks.
+
+Alternatively you can type @kbd{M-x display-fill-column-indicator-mode} or 
+@kbd{M-x global-display-fill-column-indicator-mode} which enables the indicator
+locally and globally respectively and also chooses the character to
+use if none is set. It is possible to use the first one to activate the 
+indicator in a hook or the second one to enable it globally.
+
+There are 2 new buffer local variables and 1 face to customize this
+mode:
+
+@table @code
+@item display-fill-column-indicator-column
+@vindex display-fill-column-indicator-column
+Is the column number where the indicator should be set. It can take
+positive numerical values for the column or the special value t which
+means that the variable 'fill-column' will be used.
+
+Any other value disables the indicator. The default value is t.
+
+@item display-fill-column-indicator-char
+@vindex display-fill-column-indicator-char
+Is the character used for the indicator. This character can be any
+valid char including unicode ones if the actual font supports them.
+    
+When the mode is enabled throw the functions
+@code{display-fill-column-indicator-mode} or
+@code{global-display-fill-column-indicator-mode}, the initialization
+functions check if this variable is non-nil, otherwise the
+initialization tries to set it to U+2502 or '|'.
+    
+@item fill-column-face 
+Is the face used to display the indicator it inherits its default
+values from shadow and the default face.
+@end table
+
 @vindex indicate-buffer-boundaries
   On graphical displays, Emacs can indicate the buffer boundaries in
 the fringes.  If you enable this feature, the first line and the last