bug#41343: tab-bar-mode: Close tab on mouse-2 click

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Date: Wed, 04 Aug 2021 01:33:45 +0300
> Cc: 41343@debbugs.gnu.org
> 
> > Please consider adding a binding to close a tab in tab-bar-mode by
> > clicking on it using the middle mouse button (mouse-2).
> 
> Here's the patch that implements mouse-2 tab closing:

Do we really have to hard-code the mouse button this way, including
explicit values in C?  Why is that necessary or justified?