* dispnew.c (scrolling_window): Don't exclude the case that the

last enabled row in the desired matrix touches the bottom boundary.

src/ChangeLog

+2011-05-21  YAMAMOTO Mitsuharu  <mituharu@math.s.chiba-u.ac.jp>
+
+	* dispnew.c (scrolling_window): Don't exclude the case that the
+	last enabled row in the desired matrix touches the bottom boundary.
+
 2011-05-11  Drew Adams  <drew.adams@oracle.com>
 
 	* textprop.c (Fprevious_single_char_property_change): Doc fix (bug#8655).

src/dispnew.c

@@ -4990,23 +4990,29 @@ scrolling_window (w, header_line_p)
 
   first_old = first_new = i;
 
-  /* Set last_new to the index + 1 of the last enabled row in the
-     desired matrix.  */
+  /* Set last_new to the index + 1 of the row that reaches the
+     bottom boundary in the desired matrix.  Give up if we find a
+     disabled row before we reach the bottom boundary.  */
   i = first_new + 1;
-  while (i < desired_matrix->nrows - 1
-	 && MATRIX_ROW (desired_matrix, i)->enabled_p
-	 && MATRIX_ROW_BOTTOM_Y (MATRIX_ROW (desired_matrix, i)) <= yb)
-    ++i;
+  while (i < desired_matrix->nrows - 1)
+    {
+      int bottom;
 
-  if (!MATRIX_ROW (desired_matrix, i)->enabled_p)
-    return 0;
+      if (!MATRIX_ROW (desired_matrix, i)->enabled_p)
+	return 0;
+      bottom = MATRIX_ROW_BOTTOM_Y (MATRIX_ROW (desired_matrix, i));
+      if (bottom <= yb)
+	++i;
+      if (bottom >= yb)
+	break;
+    }
 
   last_new = i;
 
-  /* Set last_old to the index + 1 of the last enabled row in the
-     current matrix.  We don't look at the enabled flag here because
-     we plan to reuse part of the display even if other parts are
-     disabled.  */
+  /* Set last_old to the index + 1 of the row that reaches the bottom
+     boundary in the current matrix.  We don't look at the enabled
+     flag here because we plan to reuse part of the display even if
+     other parts are disabled.  */
   i = first_old + 1;
   while (i < current_matrix->nrows - 1)
     {