Improve documentation of how vertical-motion interprets columns.

 src/indent.c (Fvertical_motion): Doc fix.

 doc/lispref/positions.texi (Screen Lines): Clarify how columns are counted
 by vertical-motion.

2 files changed, 10 insertions, 1 deletions

diff --git a/doc/lispref/ChangeLog b/doc/lispref/ChangeLog
index c20a20409a2..4610c33796a 100644
--- a/doc/lispref/ChangeLog
+++ b/doc/lispref/ChangeLog
@@ -1,3 +1,8 @@
+2014-06-21  Eli Zaretskii  <eliz@gnu.org>
+
+        * positions.texi (Screen Lines): Clarify how columns are counted
+        by vertical-motion.
+
 2014-06-14  Eli Zaretskii  <eliz@gnu.org>
 
         * commands.texi (Accessing Mouse): Improve the wording of the
diff --git a/doc/lispref/positions.texi b/doc/lispref/positions.texi
index f83173e2038..fee36fa833d 100644
--- a/doc/lispref/positions.texi
+++ b/doc/lispref/positions.texi
@@ -500,7 +500,11 @@ is negative, it moves up instead.
 The @var{count} argument can be a cons cell, @code{(@var{cols}
 . @var{lines})}, instead of an integer.  Then the function moves by
 @var{lines} screen lines, and puts point @var{cols} columns from the
-start of that screen line.
+visual start of that screen line.  Note that @var{cols} are counted
+from the @emph{visual} start of the line; if the window is scrolled
+horizontally (@pxref{Horizontal Scrolling}), the column on which point
+will end is in addition to the number of columns by which the text is
+scrolled.
 
 The return value is the number of screen lines over which point was
 moved.  The value may be less in absolute value than @var{count} if