Fix bug #9607 with vertical motion when auto-hscroll-mode is disabled.

 lisp/simple.el (line-move): If auto-hscroll-mode is disabled and the
 window is hscrolled, move by logical lines.
 (line-move-visual): Update the doc string to the above effect.

2 files changed, 18 insertions, 2 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index b217a9093f6..42bd14094ba 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,9 @@
+2011-09-29  Eli Zaretskii  <eliz@gnu.org>
+
+        * simple.el (line-move): If auto-hscroll-mode is disabled and the
+        window is hscrolled, move by logical lines.  (Bug#9607)
+        (line-move-visual): Update the doc string to the above effect.
+
 2011-09-29  Martin Rudalics  <rudalics@gmx.at>
 
         * window.el (display-buffer-record-window): When WINDOW is the
diff --git a/lisp/simple.el b/lisp/simple.el
index 14ce5ed18ec..1ab90792bfa 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -4244,7 +4244,9 @@ screen, instead of relying on buffer contents alone.  It takes
 into account variable-width characters and line continuation.
 If nil, `line-move' moves point by logical lines.
 A non-nil setting of `goal-column' overrides the value of this variable
-and forces movement by logical lines."
+and forces movement by logical lines.
+Disabling `auto-hscroll-mode' also overrides forces movement by logical
+lines when the window is horizontally scrolled."
   :type 'boolean
   :group 'editing-basics
   :version "23.1")
@@ -4321,7 +4323,15 @@ and forces movement by logical lines."
                (not executing-kbd-macro)
                (line-move-partial arg noerror to-end))
     (set-window-vscroll nil 0 t)
-    (if (and line-move-visual (not goal-column))
+    (if (and line-move-visual
+             ;; Display-based column are incompatible with goal-column.
+             (not goal-column)
+             ;; When auto-hscroll-mode is turned off and the text in
+             ;; the window is scrolled to the left, display-based
+             ;; motion doesn't make sense (because each logical line
+             ;; occupies exactly one screen line).
+             (not (and (null auto-hscroll-mode)
+                       (> (window-hscroll) 0))))
         (line-move-visual arg noerror)
       (line-move-1 arg noerror to-end))))