Re: src/nsterm.m: fix window tabbing on macOS

[martin rudalics]

> All Emacs frames are grouped in single window manager window.  I refer
> to that window manager window as frame.

I'm afraid that will confuse us.  Let's call that WM-frame.

> Initially the tab bar is hidden.  After new frame created (s-n), the tab
> bar is shown with two tabs,

Why?  Have you `tab-bar-mode' turned on or have you set the
`tab-bar-lines' frame parameter?

> frame height is increased by the tab bar
> height.

That's intentional: We do that to produce the initial frame height as
specified.  What does (frame-height) give after that frame has become
visible?

> After frame deleted (s-w), tab bar become hidden again but
> frame height is not decreased.

That's intentional again.  If the tab bar has been shown once, the
"native" height of its frame should remain constant when toggling or
wrapping the tab bar.  Just like the internal tool bar on Lucid or
Windows builds.

martin