Fix bug #18384 with incorrect reporting of row number by posn-col-row.

 lisp/subr.el (posn-col-row): Revert the change from commit
 2010-11-13T21:07:58Z!eliz@gnu.org, which
 was inadvertently merged from emacs-23 release branch in 
2010-11-18T03:54:14Z!monnier@iro.umontreal.ca, and
 introduced an off-by-one error in the reported row when there is a
 header line.

 src/dispnew.c (buffer_posn_from_coords): Fix an off-by-one error in
 the reported row in the case of a window with a header line, by
 improving on the fix committed in 2011-10-08T10:58:50Z!eliz@gnu.org
 eliz@gnu.org-20111008105850-ht4tvsayohvr1kjc.

2 files changed, 15 insertions, 8 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 5e3ec8aa597..5f00b654261 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,10 @@
+2014-09-02  Eli Zaretskii  <eliz@gnu.org>
+
+        * dispnew.c (buffer_posn_from_coords): Fix an off-by-one error in
+        the reported row in the case of a window with a header line, by
+        improving on the fix committed in 2011-10-08T10:58:50Z!eliz@gnu.org
+        eliz@gnu.org-20111008105850-ht4tvsayohvr1kjc.  (Bug#18384)
+
 2014-09-02  Paul Eggert  <eggert@cs.ucla.edu>
 
         * eval.c (internal_lisp_condition_case): Don't overrun the stack
diff --git a/src/dispnew.c b/src/dispnew.c
index e6ab5bf1e9c..9725068c72b 100644
--- a/src/dispnew.c
+++ b/src/dispnew.c
@@ -5107,7 +5107,7 @@ buffer_posn_from_coords (struct window *w, int *x, int *y, struct display_pos *p
 #ifdef HAVE_WINDOW_SYSTEM
   struct image *img = 0;
 #endif
-  int x0, x1, to_x;
+  int x0, x1, to_x, it_vpos;
   void *itdata = NULL;
 
   /* We used to set current_buffer directly here, but that does the
@@ -5116,11 +5116,6 @@ buffer_posn_from_coords (struct window *w, int *x, int *y, struct display_pos *p
   itdata = bidi_shelve_cache ();
   CLIP_TEXT_POS_FROM_MARKER (startp, w->start);
   start_display (&it, w, startp);
-  /* start_display takes into account the header-line row, but IT's
-     vpos still counts from the glyph row that includes the window's
-     start position.  Adjust for a possible header-line row.  */
-  it.vpos += WINDOW_WANTS_HEADER_LINE_P (w);
-
   x0 = *x;
 
   /* First, move to the beginning of the row corresponding to *Y.  We
@@ -5190,8 +5185,13 @@ buffer_posn_from_coords (struct window *w, int *x, int *y, struct display_pos *p
     }
 #endif
 
-  if (it.vpos < w->current_matrix->nrows
-      && (row = MATRIX_ROW (w->current_matrix, it.vpos),
+  /* IT's vpos counts from the glyph row that includes the window's
+     start position, i.e. it excludes the header-line row, but
+     MATRIX_ROW includes the header-line row.  Adjust for a possible
+     header-line row.  */
+  it_vpos = it.vpos + WINDOW_WANTS_MODELINE_P (w);
+  if (it_vpos < w->current_matrix->nrows
+      && (row = MATRIX_ROW (w->current_matrix, it_vpos),
           row->enabled_p))
     {
       if (it.hpos < row->used[TEXT_AREA])