bug#22000: Patch addressing the menu-bar frame-resize interaction

[martin rudalics]

> New patch series - I think this has all the features and functionality
> discussed so far.

Everything's alright with two nitpicks:

(1) The version tag of 'menu-bar-scrollbar-mode' must be 26.2 unless Eli
decides that this may go to master only.

(2) Please make the 'showhide-menu-bar-scrollbar-menu' dependent on
whether GTK is used.  Something like

(when (featurep 'gtk)
  (defvar menu-bar-showhide-menu-bar-scrollbar-mode-menu

and

    (when (featurep 'gtk)
      (bindings--define-key menu [showhide-menu-bar-scrollbar-menu]

Eli, I think this should go to the release branch.  If it introduces any
problems, we should find out soon enough - I think that most of our GTK
users leave the menu bar on.  But it is not just a cosmetic change.  It
would have helped if anyone else tested this but unfortunately this was
not the case.

martin