Documentation of tab-bar-show and friends

[Eli Zaretskii]

The current documentation of this seems to be incomplete and for some
reason hides some of the functionality.

First, the NEWS entry for tab-bar-show says:

  *** The tab bar is frame-local when 'tab-bar-show' is a number.
  Show/hide the tab bar independently for each frame, according to the
  value of 'tab-bar-show'.

What does it mean "frame-local" in this case?  Does it mean one should
use a frame parameter called tab-bar-show?  Or does it mean something
else?

Next, the above says "a number", but the doc string of tab-bar-show,
the defcustom forms, and the manual only describe one value: 1.
However, the code does:

   ((natnump tab-bar-show)
    (if (> (length (funcall tab-bar-tabs-function frame)) tab-bar-show) 1 0))))

So tab-bar-show can be meaningfully set to a number other than 1.
This is undocumented, for some reason.  Is that intentional?

Please help me rectify these problems.

Thanks.