> This is using Emacs 27.2 on a CentOS8 machine at work. I use Emacs
> exclusively with -nw in a terminal with mouse support enabled.
>
> Using something like
>
> (setq tab-line-separator " | ")
>
> breaks the ability to click on a tab to select it. Leaving it at the
> default value avoids the bug.

Sorry, tab-line had hard-coded assumption on separators
no longer than 1 character wide.

Eli, is it ok to push this patch to the release branch
to support longer separators: