Fix line-move-visual's following of column in R2L lines (backport from trunk).

 src/simple.el (line-move-visual): When converting X pixel coordinate
 to temporary-goal-column, adjust the value for right-to-left
 screen lines.  This fixes vertical-motion, next/prev-line, etc.

 src/dispnew.c (buffer_posn_from_coords): Fix the value of the column
 returned for right-to-left screen lines.  (Before the change on
 2014-12-30, the incorrectly-computed X pixel coordinate concealed
 this bug.)

(cherry picked from commit 5fbd17e369ca30a47ab8a2eda0b2f2ea9b690bb4)

Conflicts:
	lisp/simple.el

2 files changed, 18 insertions, 3 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 73aa3e023b7..2a6c960c4be 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,9 @@
+2015-01-08  Eli Zaretskii  <eliz@gnu.org>
+
+        * simple.el (line-move-visual): When converting X pixel coordinate
+        to temporary-goal-column, adjust the value for right-to-left
+        screen lines.  This fixes vertical-motion, next/prev-line, etc.
+
 2015-01-06  Glenn Morris  <rgm@gnu.org>
 
         * progmodes/sh-script.el (sh-mode): Doc fix.
diff --git a/lisp/simple.el b/lisp/simple.el
index 0a1b6336f5f..497e4a1604f 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -5254,15 +5254,24 @@ If NOERROR, don't signal an error if we can't move that many lines."
                 (>  (cdr temporary-goal-column) 0))
             (setq target-hscroll (cdr temporary-goal-column)))
       ;; Otherwise, we should reset `temporary-goal-column'.
-      (let ((posn (posn-at-point)))
+      (let ((posn (posn-at-point))
+            x-pos)
         (cond
          ;; Handle the `overflow-newline-into-fringe' case:
          ((eq (nth 1 posn) 'right-fringe)
           (setq temporary-goal-column (cons (- (window-width) 1) hscroll)))
          ((car (posn-x-y posn))
+          (setq x-pos (car (posn-x-y posn)))
+          ;; In R2L lines, the X pixel coordinate is measured from the
+          ;; left edge of the window, but columns are still counted
+          ;; from the logical-order beginning of the line, i.e. from
+          ;; the right edge in this case.  We need to adjust for that.
+          (if (eq (current-bidi-paragraph-direction) 'right-to-left)
+              (setq x-pos (- (window-body-width nil t) 1 x-pos)))
           (setq temporary-goal-column
-                (cons (/ (float (car (posn-x-y posn)))
-                         (frame-char-width)) hscroll))))))
+                (cons (/ (float x-pos)
+                         (frame-char-width))
+                      hscroll))))))
     (if target-hscroll
         (set-window-hscroll (selected-window) target-hscroll))
     ;; vertical-motion can move more than it was asked to if it moves