bug#49247: 28.0.50; [Feature Request] Make tab-bar-lines dragable

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Cc: martin rudalics <rudalics@gmx.at>,  49247@debbugs.gnu.org,
>   s930054123yaoyao@gmail.com
> Date: Sun, 04 Jul 2021 23:37:21 +0300
> 
> There were also user requests to change the mouse pointer shape
> to ‘hand’ when the mouse pointer is over the tab-bar tabs,
> the same way as currently the mouse pointer changes to ‘hand’
> when it's over the tab-line tabs.
> 
> I guess this will also require significant changes in how
> mouse mouse motion events on the tab-bar are processed?

No, I think you need to change only a little in
note_tab_bar_highlight for this.