Don't use hook pre-redisplay-functions. Set buffer-local tab-line-format.

* lisp/tab-line.el (tab-line-format): Move to C.
(tab-line-update-window-parameter): Remove function.
(global-tab-line-mode): Set the default value of tab-line-format.

* src/buffer.c (syms_of_buffer): Define buffer-local variable
tab-line-format.

* src/buffer.h (struct buffer): Add tab_line_format_.

* src/window.c (window_wants_tab_line):
* src/xdisp.c (pos_visible_p, display_mode_lines):
Check for buffer-local tab_line_format.

1 files changed, 2 insertions, 1 deletions

diff --git a/src/window.c b/src/window.c
index 30b53d1a06d..6749ffde4c1 100644
--- a/src/window.c
+++ b/src/window.c
@@ -5419,7 +5419,8 @@ window_wants_tab_line (struct window *w)
            && !MINI_WINDOW_P (w)
            && !WINDOW_PSEUDO_P (w)
            && !EQ (window_tab_line_format, Qnone)
-           && !NILP (window_tab_line_format)
+           && (!NILP (window_tab_line_format)
+               || !NILP (BVAR (XBUFFER (WINDOW_BUFFER (w)), tab_line_format)))
            && (WINDOW_PIXEL_HEIGHT (w)
                > (((window_wants_mode_line (w) ? 1 : 0)
                    + (window_wants_header_line (w) ? 1 : 0)