master 96b21b8da1: Clarify computation of header line vpos

[Po Lu]

branch: master
commit 96b21b8da10e4e31981e8a6874411ab184259fa4
Author: Po Lu <luangruo@yahoo.com>
Commit: Po Lu <luangruo@yahoo.com>

    Clarify computation of header line vpos
    
    * src/dispnew.c (update_text_area): Test vpos is more than 1
    only if is both a tab and header line.  Reported by Eli
    Zaretskii <eliz@gnu.org>.
---
 src/dispnew.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/dispnew.c b/src/dispnew.c
index 3cfe1b86f6..2aba0edfe8 100644
--- a/src/dispnew.c
+++ b/src/dispnew.c
@@ -3933,7 +3933,8 @@ update_text_area (struct window *w, struct glyph_row 
*updated_row, int vpos)
          Apr 2022) */
       || (current_row->mouse_face_p
          && !(current_row->mode_line_p
-              && (vpos > w->current_matrix->tab_line_p)))
+              && (vpos > (w->current_matrix->tab_line_p
+                          && w->current_matrix->header_line_p))))
       || current_row->x != desired_row->x)
     {
       output_cursor_to (w, vpos, 0, desired_row->y, desired_row->x);