>  > Because tabs have priority over frames.  The precedence is:
>  > windows -> tabs -> frames.  When there are many tabs
>  > then quit-restore-window should close tabs, and only
>  > on the last tab should delete the frame.  This is bug#71386,
>  > but first need to finish bug#59862.
>
> So which bug are we discussing here?  Bug#59862 or Bug#71386?

I intended to finish first bug#59862, then to do bug#71386 later.
But really they are closely related, so I fixed them both now
and added corresponding references to bug numbers in comments.

>  >> I don't understand the problem yet.  'window-deletable-p' calls
>  >> 'frame-deletable-p' iff WINDOW is the root window of the frame.  At this
>  >> time we can only either delete the frame or show another buffer in
>  >> WINDOW; tertium non datur.  What am I missing?
>  >
>  > The third first-class citizen is the tab-bar.
>
> But I haven't written anything for the tab-bar code.  This is something
> you have to provide.  Earlier you proposed

So I extended this patch, and now all tests pass successfully with: