bug#63271: 29.0.90; broken mouse-face

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Date: Thu, 04 May 2023 18:11:18 +0300
> 
> This is a regression introduced between 28 and 29.
> 
> 1. M-x global-tab-line-mode RET
> 2. C-h C-n   ;; (view-emacs-news)
> 3. C-h C-t   ;; (view-emacs-todo)
> 4. C-x b *scratch* RET
> 
> Hover the mouse pointer over the tabs.
> Over all tabs mouse-face is 'tab-line-highlight'
> that is light grey color.  But over the "TODO" tab
> the main text is not highlighted with mouse-face.
> There is no difference between "NEWS" and "TODO"
> with regard to their text properties.
> Customizing 'tab-line-highlight' to a more noticeable
> background color like red helps the observe the effect.

I cannot reproduce this with the current emacs-29 branch.  All tabs
behave the same as far as mouse-highlight is concerned.

Maybe this is specific to X or GTK?  (Why don't you post the details
of your build and configuration, as collected by report-emacs-bug?)