emacs-29 ca43435816b: Fix redisplay of mode line after its format changes from nil

[Eli Zaretskii]

branch: emacs-29
commit ca43435816b7c7ceaef1a6fce967cbdbcf243ea3
Author: Eli Zaretskii <eliz@gnu.org>
Commit: Eli Zaretskii <eliz@gnu.org>

    Fix redisplay of mode line after its format changes from nil
    
    * src/dispnew.c (update_window): Make sure a mode-line's row of
    the current glyph matrix is disabled when the mode line is not
    being displayed.  (Bug#63186)
---
 src/dispnew.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/dispnew.c b/src/dispnew.c
index 87ec83acdf3..65d9cf9b4e1 100644
--- a/src/dispnew.c
+++ b/src/dispnew.c
@@ -3748,6 +3748,14 @@ update_window (struct window *w, bool force_p)
              }
          }
 
+      /* If the window doesn't display its mode line, make sure the
+         corresponding row of the current glyph matrix is disabled, so
+         that if and when the mode line is displayed again, it will be
+         cleared and completely redrawn.  */
+      if (!window_wants_mode_line (w))
+       SET_MATRIX_ROW_ENABLED_P (w->current_matrix,
+                                 w->current_matrix->nrows - 1, false);
+
       /* Was display preempted?  */
       paused_p = row < end;