>
>
> So it's a hook parameter, part of state kept by the tab. Right.



If the hok 'initialize-tab produce that variable local to tab, I cannot see
how to send this variable to the hooks 'show-tab or 'kill-tab that uses it,
via parameters of hooks.


In the same time, ideally if that this variable be hidden to global env,
because no other part of emacs needs it, apart from the hooks of the tab...