Subject: bug#51830: 29.0.50; tab-line-mode will override (setq-default tab-line-format "xxx")

From: Lars Ingebrigtsen <[email-masked]>
Date: Sun, 14 Nov 2021 07:33:36 +0100

"Feng Shu" <[email-masked]> writes:

> (setq tab-line-format "xxx")
> (global-tab-line-mode 1)
>
> value "xxx"  will lost.

Yes, tab-line-mode resets the variable unconditionally:

(define-minor-mode tab-line-mode
  "Toggle display of tab line in the windows displaying the current buffer."
  :lighter nil
  (setq tab-line-format (when tab-line-mode '(:eval (tab-line-format)))))

Perhaps that should be done only when the variable's value is nil?
(I've added Juri to the CCs.)

-- 
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   bloggy blog: http://lars.ingebrigtsen.no