As far as I remember that option was removed after CB7 and the option was never brought back. Most likely because they incorp’d the lower zone mixer (which I never use). Maybe it is time for a new feature request.
It was removed when they made it possible to maximize the mixer window in Cubase 8 due to some workflow-ruining window z-ordering issues in Cubase 7.5.
I never quite understand why they remove things that are optional. Surely there is no gain to removing something that some users have got used to.
Another example is the Dual Pan option. I used to always use it as my preferred panning option in the mixer and then for whatever reason after years and years they remove it.
I can no longer change bpm while working in the editor in seperate window mode (as opposed to lower zone) without the editor window disappearing, so essentially can’t do any time correction with audio parts ?