2 files changed, 29 insertions, 1 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 7352d8e0081..2f3643f4f80 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -14,6 +14,9 @@
         proceed to consider_string_end without incrementing string
         position.  Don't increment display vector index past the end of
         the display vector.  (Bug#11417)
+        (pos_visible_p): Don't report a position visible when move_it_to
+        stopped at the last line of window, which happens to be scanned
+        backwards by the bidi iteration.  (Bug#11464)
 
 2012-05-11  Eli Zaretskii  <eliz@gnu.org>
 
diff --git a/src/xdisp.c b/src/xdisp.c
index b1e2a925bce..a2c4589766d 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -1304,8 +1304,8 @@ pos_visible_p (struct window *w, EMACS_INT charpos, int *x, int *y,
          glyph.  */
       int top_x = it.current_x;
       int top_y = it.current_y;
-      enum it_method it_method = it.method;
       /* Calling line_bottom_y may change it.method, it.position, etc.  */
+      enum it_method it_method = it.method;
       int bottom_y = (last_height = 0, line_bottom_y (&it));
       int window_top_y = WINDOW_HEADER_LINE_HEIGHT (w);
 
@@ -1313,6 +1313,31 @@ pos_visible_p (struct window *w, EMACS_INT charpos, int *x, int *y,
         visible_p = bottom_y > window_top_y;
       else if (top_y < it.last_visible_y)
         visible_p = 1;
+      if (bottom_y >= it.last_visible_y
+          && it.bidi_p && it.bidi_it.scan_dir == -1
+          && IT_CHARPOS (it) < charpos)
+        {
+          /* When the last line of the window is scanned backwards
+             under bidi iteration, we could be duped into thinking
+             that we have passed CHARPOS, when in fact move_it_to
+             simply stopped short of CHARPOS because it reached
+             last_visible_y.  To see if that's what happened, we call
+             move_it_to again with a slightly larger vertical limit,
+             and see if it actually moved vertically; if it did, we
+             didn't really reach CHARPOS, which is beyond window end.  */
+          struct it save_it = it;
+          /* Why 10? because we don't know how many canonical lines
+             will the height of the next line(s) be.  So we guess.  */
+          int ten_more_lines =
+            10 * FRAME_LINE_HEIGHT (XFRAME (WINDOW_FRAME (w)));
+
+          move_it_to (&it, charpos, -1, bottom_y + ten_more_lines, -1,
+                      MOVE_TO_POS | MOVE_TO_Y);
+          if (it.current_y > top_y)
+            visible_p = 0;
+
+          it = save_it;
+        }
       if (visible_p)
         {
           if (it_method == GET_FROM_DISPLAY_VECTOR)