1 files changed, 73 insertions, 19 deletions

diff --git a/src/xdisp.c b/src/xdisp.c
index 83e84861425..39940ec3f56 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -19887,9 +19887,7 @@ draw_glyphs (w, x, row, area, start, end, hl, overlaps)
   struct glyph_string *head, *tail;
   struct glyph_string *s;
   struct glyph_string *clip_head = NULL, *clip_tail = NULL;
-  int last_x, area_width;
-  int x_reached;
-  int i, j;
+  int i, j, x_reached, last_x, area_left = 0;
   struct frame *f = XFRAME (WINDOW_FRAME (w));
   DECLARE_HDC (hdc);
 
@@ -19906,16 +19904,15 @@ draw_glyphs (w, x, row, area, start, end, hl, overlaps)
     {
       /* X is relative to the left edge of W, without scroll bars
          or fringes.  */
-      x += WINDOW_LEFT_EDGE_X (w);
+      area_left = WINDOW_LEFT_EDGE_X (w);
       last_x = WINDOW_LEFT_EDGE_X (w) + WINDOW_TOTAL_WIDTH (w);
     }
   else
     {
-      int area_left = window_box_left (w, area);
-      x += area_left;
-      area_width = window_box_width (w, area);
-      last_x = area_left + area_width;
+      area_left = window_box_left (w, area);
+      last_x = area_left + window_box_width (w, area);
     }
+  x += area_left;
 
   /* Build a doubly-linked list of glyph_string structures between
      head and tail from what we have to draw.  Note that the macro
@@ -19933,8 +19930,30 @@ draw_glyphs (w, x, row, area, start, end, hl, overlaps)
      strings built above.  */
   if (head && !overlaps && row->contains_overlapping_glyphs_p)
     {
-      int dummy_x = 0;
       struct glyph_string *h, *t;
+      Display_Info *dpyinfo = FRAME_X_DISPLAY_INFO (f);
+      int mouse_beg_col, mouse_end_col, check_mouse_face = 0;
+      int dummy_x = 0;
+
+      /* If mouse highlighting is on, we may need to draw adjacent
+         glyphs using mouse-face highlighting.  */
+      if (area == TEXT_AREA && row->mouse_face_p)
+        {
+          struct glyph_row *mouse_beg_row, *mouse_end_row;
+
+          mouse_beg_row = MATRIX_ROW (w->current_matrix, dpyinfo->mouse_face_beg_row);
+          mouse_end_row = MATRIX_ROW (w->current_matrix, dpyinfo->mouse_face_end_row);
+
+          if (row >= mouse_beg_row && row <= mouse_end_row)
+            {
+              check_mouse_face = 1;
+              mouse_beg_col = (row == mouse_beg_row)
+                ? dpyinfo->mouse_face_beg_col : 0;
+              mouse_end_col = (row == mouse_end_row)
+                ? dpyinfo->mouse_face_end_col
+                : row->used[TEXT_AREA];
+            }
+        }
 
       /* Compute overhangs for all glyph strings.  */
       if (FRAME_RIF (f)->compute_glyph_string_overhangs)
@@ -19949,10 +19968,24 @@ draw_glyphs (w, x, row, area, start, end, hl, overlaps)
       i = left_overwritten (head);
       if (i >= 0)
         {
+          enum draw_glyphs_face overlap_hl;
+
+          /* If this row contains mouse highlighting, attempt to draw
+             the overlapped glyphs with the correct highlight.  This
+             code fails if the overlap encompasses more than one glyph
+             and mouse-highlight spans only some of these glyphs.
+             However, making it work perfectly involves a lot more
+             code, and I don't know if the pathological case occurs in
+             practice, so we'll stick to this for now.  --- cyd  */
+          if (check_mouse_face
+              && mouse_beg_col < start && mouse_end_col > i)
+            overlap_hl = DRAW_MOUSE_FACE;
+          else
+            overlap_hl = DRAW_NORMAL_TEXT;
+
           j = i;
           BUILD_GLYPH_STRINGS (j, start, h, t,
-                               DRAW_NORMAL_TEXT, dummy_x, last_x);
-          start = i;
+                               overlap_hl, dummy_x, last_x);
           compute_overhangs_and_x (t, head->x, 1);
           prepend_glyph_string_lists (&head, &tail, h, t);
           clip_head = head;
@@ -19968,9 +20001,17 @@ draw_glyphs (w, x, row, area, start, end, hl, overlaps)
       i = left_overwriting (head);
       if (i >= 0)
         {
+          enum draw_glyphs_face overlap_hl;
+
+          if (check_mouse_face
+              && mouse_beg_col < start && mouse_end_col > i)
+            overlap_hl = DRAW_MOUSE_FACE;
+          else
+            overlap_hl = DRAW_NORMAL_TEXT;
+
           clip_head = head;
           BUILD_GLYPH_STRINGS (i, start, h, t,
-                               DRAW_NORMAL_TEXT, dummy_x, last_x);
+                               overlap_hl, dummy_x, last_x);
           for (s = h; s; s = s->next)
             s->background_filled_p = 1;
           compute_overhangs_and_x (t, head->x, 1);
@@ -19984,8 +20025,16 @@ draw_glyphs (w, x, row, area, start, end, hl, overlaps)
       i = right_overwritten (tail);
       if (i >= 0)
         {
+          enum draw_glyphs_face overlap_hl;
+
+          if (check_mouse_face
+              && mouse_beg_col < i && mouse_end_col > end)
+            overlap_hl = DRAW_MOUSE_FACE;
+          else
+            overlap_hl = DRAW_NORMAL_TEXT;
+
           BUILD_GLYPH_STRINGS (end, i, h, t,
-                               DRAW_NORMAL_TEXT, x, last_x);
+                               overlap_hl, x, last_x);
           compute_overhangs_and_x (h, tail->x + tail->width, 0);
           append_glyph_string_lists (&head, &tail, h, t);
           clip_tail = tail;
@@ -19999,10 +20048,17 @@ draw_glyphs (w, x, row, area, start, end, hl, overlaps)
       i = right_overwriting (tail);
       if (i >= 0)
         {
+          enum draw_glyphs_face overlap_hl;
+          if (check_mouse_face
+              && mouse_beg_col < i && mouse_end_col > end)
+            overlap_hl = DRAW_MOUSE_FACE;
+          else
+            overlap_hl = DRAW_NORMAL_TEXT;
+
           clip_tail = tail;
           i++;                  /* We must include the Ith glyph.  */
           BUILD_GLYPH_STRINGS (end, i, h, t,
-                               DRAW_NORMAL_TEXT, x, last_x);
+                               overlap_hl, x, last_x);
           for (s = h; s; s = s->next)
             s->background_filled_p = 1;
           compute_overhangs_and_x (h, tail->x + tail->width, 0);
@@ -20030,10 +20086,8 @@ draw_glyphs (w, x, row, area, start, end, hl, overlaps)
       int x0 = clip_head ? clip_head->x : (head ? head->x : x);
       int x1 = (clip_tail ? clip_tail->x + clip_tail->background_width
                 : (tail ? tail->x + tail->background_width : x));
-
-      int text_left = window_box_left (w, TEXT_AREA);
-      x0 -= text_left;
-      x1 -= text_left;
+      x0 -= area_left;
+      x1 -= area_left;
 
       notice_overwritten_cursor (w, TEXT_AREA, x0, x1,
                                  row->y, MATRIX_ROW_BOTTOM_Y (row));
@@ -20044,7 +20098,7 @@ draw_glyphs (w, x, row, area, start, end, hl, overlaps)
   if (row->full_width_p)
     x_reached = FRAME_TO_WINDOW_PIXEL_X (w, x_reached);
   else
-    x_reached -= window_box_left (w, area);
+    x_reached -= area_left;
 
   RELEASE_HDC (hdc, f);