(try_window_reusing_current_matrix):

Handle the case where we reach the old displayed text,
out of sync with the old line boundary.

2 files changed, 42 insertions, 6 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 955c8929f92..3d8cfd61200 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,9 @@
+2004-09-18  Richard M. Stallman  <rms@gnu.org>
+
+        * xdisp.c (try_window_reusing_current_matrix):
+        Handle the case where we reach the old displayed text,
+        out of sync with the old line boundary.
+
 2004-09-14  Stefan  <monnier@iro.umontreal.ca>
 
         * fileio.c (Finsert_file_contents): Fix case of replacement in a
diff --git a/src/xdisp.c b/src/xdisp.c
index 496e79d194a..874f1951256 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -12404,10 +12404,36 @@ try_window_reusing_current_matrix (w)
       last_text_row = last_reused_text_row = NULL;
 
       while (it.current_y < it.last_visible_y
-             && IT_CHARPOS (it) < CHARPOS (start)
              && !fonts_changed_p)
-        if (display_line (&it))
-          last_text_row = it.glyph_row - 1;
+        {
+          /* If we have reached into the characters in the START row,
+             that means the line boundaries have changed.  So we
+             can't start copying with the row START.  Maybe it will
+             work to start copying with the following row.  */
+          while (IT_CHARPOS (it) > CHARPOS (start))
+            {
+              /* Advance to the next row as the "start".  */
+              start_row++;
+              start = start_row->start.pos;
+              /* If there are no more rows to try, or just one, give up.  */
+              if (start_row == MATRIX_MODE_LINE_ROW (w->current_matrix) - 1
+                  || w->vscroll || MATRIX_ROW_PARTIALLY_VISIBLE_P (start_row)
+                  || CHARPOS (start) == ZV)
+                {
+                  clear_glyph_matrix (w->desired_matrix);
+                  return 0;
+                }
+
+              start_vpos = MATRIX_ROW_VPOS (start_row, w->current_matrix);
+            }
+          /* If we have reached alignment,
+             we can copy the rest of the rows.  */
+          if (IT_CHARPOS (it) == CHARPOS (start))
+            break;
+
+          if (display_line (&it))
+            last_text_row = it.glyph_row - 1;
+        }
 
       /* A value of current_y < last_visible_y means that we stopped
          at the previous window start, which in turn means that we
@@ -12415,12 +12441,12 @@ try_window_reusing_current_matrix (w)
       if (it.current_y < it.last_visible_y)
         {
           /* IT.vpos always starts from 0; it counts text lines.  */
-          nrows_scrolled = it.vpos;
+          nrows_scrolled = it.vpos - (start_row - MATRIX_FIRST_TEXT_ROW (w->current_matrix));
 
           /* Find PT if not already found in the lines displayed.  */
           if (w->cursor.vpos < 0)
             {
-              int dy = it.current_y - first_row_y;
+              int dy = it.current_y - start_row->y;
 
               row = MATRIX_FIRST_TEXT_ROW (w->current_matrix);
               row = row_containing_pos (w, PT, row, NULL, dy);
@@ -12440,7 +12466,7 @@ try_window_reusing_current_matrix (w)
              scroll_run_hook will clear the cursor, and use the
              current matrix to get the height of the row the cursor is
              in.  */
-          run.current_y = first_row_y;
+          run.current_y = start_row->y;
           run.desired_y = it.current_y;
           run.height = it.last_visible_y - it.current_y;
 
@@ -15335,6 +15361,10 @@ display_mode_element (it, depth, field_width, precision, elt, props, risky)
             Lisp_Object oprops, aelt;
             oprops = Ftext_properties_at (make_number (0), elt);
 
+            /* If the starting string's properties are not what
+               we want, translate the string.  Also, if the string
+               is risky, do that anyway.  */
+
             if (NILP (Fequal (props, oprops)) || risky)
               {
                 /* If the starting string has properties,