2 files changed, 45 insertions, 30 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 403a60a7444..49ae3e66d29 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,7 @@
 2001-01-26  Gerd Moellmann  <gerd@gnu.org>
 
+        * dispnew.c (adjust_glyph_matrix): Always clear desired matrices.
+
         * xdisp.c (display_line): Simplify check for glyphs fitting
         entirely in the line.
 
diff --git a/src/dispnew.c b/src/dispnew.c
index c0471f2a31d..c7a65823819 100644
--- a/src/dispnew.c
+++ b/src/dispnew.c
@@ -775,44 +775,57 @@ adjust_glyph_matrix (w, matrix, x, y, dim)
   matrix->nrows = dim.height;
   xassert (matrix->nrows >= 0);
 
-  /* Mark rows in a current matrix of a window as not having valid
-     contents.  It's important to not do this for desired matrices.
-     When Emacs starts, it may already be building desired matrices
-     when this function runs.  */
-  if (w && matrix == w->current_matrix)
-    {
-      if (window_width < 0)
-        window_width = window_box_width (w, -1);
-      
-      /* Optimize the case that only the height has changed (C-x 2,
-         upper window).  Invalidate all rows that are no longer part
-         of the window.  */
-      if (!marginal_areas_changed_p
-          && matrix->window_left_x == XFASTINT (w->left)
-          && matrix->window_top_y == XFASTINT (w->top)
-          && matrix->window_width == window_box_width (w, -1))
+  if (w)
+    {
+      if (matrix == w->current_matrix)
         {
-          i = 0;
-          while (matrix->rows[i].enabled_p
-                 && (MATRIX_ROW_BOTTOM_Y (matrix->rows + i)
-                     < matrix->window_height))
-            ++i;
-
-          /* Window end is invalid, if inside of the rows that
-             are invalidated.  */
-          if (INTEGERP (w->window_end_vpos)
-              && XFASTINT (w->window_end_vpos) >= i)
-            w->window_end_valid = Qnil;
+          /* Mark rows in a current matrix of a window as not having
+             valid contents.  It's important to not do this for
+             desired matrices.  When Emacs starts, it may already be
+             building desired matrices when this function runs.  */
+          if (window_width < 0)
+            window_width = window_box_width (w, -1);
+      
+          /* Optimize the case that only the height has changed (C-x 2,
+             upper window).  Invalidate all rows that are no longer part
+             of the window.  */
+          if (!marginal_areas_changed_p
+              && matrix->window_left_x == XFASTINT (w->left)
+              && matrix->window_top_y == XFASTINT (w->top)
+              && matrix->window_width == window_box_width (w, -1))
+            {
+              i = 0;
+              while (matrix->rows[i].enabled_p
+                     && (MATRIX_ROW_BOTTOM_Y (matrix->rows + i)
+                         < matrix->window_height))
+                ++i;
+
+              /* Window end is invalid, if inside of the rows that
+                 are invalidated.  */
+              if (INTEGERP (w->window_end_vpos)
+                  && XFASTINT (w->window_end_vpos) >= i)
+                w->window_end_valid = Qnil;
           
-          while (i < matrix->nrows)
-            matrix->rows[i++].enabled_p = 0;
+              while (i < matrix->nrows)
+                matrix->rows[i++].enabled_p = 0;
+            }
+          else
+            {
+              for (i = 0; i < matrix->nrows; ++i)
+                matrix->rows[i].enabled_p = 0;
+            }
         }
-      else
+      else if (matrix == w->desired_matrix)
         {
+          /* Rows in desired matrices always have to be cleared;
+             redisplay expects this is the case when it runs, so it
+             had better be the case when we adjust matrices between
+             redisplays.  */
           for (i = 0; i < matrix->nrows; ++i)
             matrix->rows[i].enabled_p = 0;
         }
     }
+    
   
   /* Remember last values to be able to optimize frame redraws.  */
   matrix->matrix_x = x;