(note_mode_line_or_margin_highlight): Don't decrement glyph pointer

before start of glyph row.

1 files changed, 12 insertions, 7 deletions

diff --git a/src/xdisp.c b/src/xdisp.c
index fd65856c8e5..90977aa3d7d 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -22437,7 +22437,7 @@ note_mode_line_or_margin_highlight (window, x, y, area)
 
   Lisp_Object mouse_face;
   int original_x_pixel = x;
-  struct glyph * glyph = NULL;
+  struct glyph * glyph = NULL, * row_start_glyph = NULL;
   struct glyph_row *row;
 
   if (area == ON_MODE_LINE || area == ON_HEADER_LINE)
@@ -22455,7 +22455,7 @@ note_mode_line_or_margin_highlight (window, x, y, area)
       /* Find glyph */
       if (row->mode_line_p && row->enabled_p)
         {
-          glyph = row->glyphs[TEXT_AREA];
+          glyph = row_start_glyph = row->glyphs[TEXT_AREA];
           end = glyph + row->used[TEXT_AREA];
 
           for (x0 = original_x_pixel;
@@ -22579,12 +22579,17 @@ note_mode_line_or_margin_highlight (window, x, y, area)
              is converted to a flatten by emacs lisp interpreter.
              The internal string is an element of the structures.
              The displayed string is the flatten string. */
-          for (tmp_glyph = glyph - 1, gpos = 0;
-               tmp_glyph->charpos >= XINT (b);
-               tmp_glyph--, gpos++)
+          gpos = 0;
+          if (glyph > row_start_glyph)
             {
-              if (!EQ (tmp_glyph->object, glyph->object))
-                break;
+              tmp_glyph = glyph - 1;
+              while (tmp_glyph >= row_start_glyph
+                     && tmp_glyph->charpos >= XINT (b)
+                     && EQ (tmp_glyph->object, glyph->object))
+                {
+                  tmp_glyph--;
+                  gpos++;
+                }
             }
 
           /* Calculate the lenght(glyph sequence length: GSEQ_LENGTH) of