>
>
> > I propose the following  [brief/ main steps of a] concrete solution for
> > changing the color of a hidden tab whose process gave output in the
> > meantime:
> >
> > 1. Every tab has a unique ID that can be read and not modified. This ID
> is
> > dubbed by the system at the creation of the tab.
>
> This is pointless. Window configurations don't need a 'unique ID',
> neither does this. Just reify the tab: make it a unique Lisp object type
> (again, like window-configurations). Now the tab object serves as its
> own unique ID.
>
>
We were talking here about a method to implement the hourglass
functionality of a tab.

Please read the previous discussion , and what means message passing in
scheme. I was talking about that.