bug#24596: 25.1; `f10' behavior

[Drew Adams]

`f10' used to just be bound to `tmm-menubar', for both TTY and
graphic-display Emacs.  Now it is bound to `menu-bar-open'.

1. User option `tty-menu-open-use-tmm' makes `f10' use `tmm-menubar'
instead, but only on TTY.  Why not also on graphic displays?  Or why not
have the option value let you choose: always `tmm-menubar', never
`tmm-menubar', or `tmm-menubar only for TTY?  (And of course rename it,
if it is made to apply to more than TTYs.)

2. Why can you not exit `menu-bar-open' (with nil
`tty-menu-open-use-tmm')?  Why is ESC the only way to cancel (at least
on MS Windows)?  Why are not the canonical Emacs ways of canceling
implemented here (`C-g' and `ESC ESC ESC')?

3. The doc string of `menu-bar-open' says nothing about the behavior.
It says nothing about what it does or what keys you can use, etc.  It
should.  Instead, it passes you off to commands `x-menu-bar-open',
`w32-menu-bar-open', `popup-menu', and `tmm-menubar'.

Are the keys you can use different for `x-menu-bar-open' and
`w32-menu-bar-open'?  The latter's doc tells you about keys you can use,
but the former's doc says nothing about keys.

Seems like the doc for `C-h k f10' should give you more info about the
behavior, and the keys you can use for the default behavior (at least).

4. The doc in the Emacs manual (node Menu Bar) is not too bad.  But
AFAICT, `C-g' does NOT work (in MS Windows), as it says it does.  It
also says that you can cancel using `ESC ESC ESC'.  But the doc of
`w32-menu-bar-open' (correctly) says that a single `ESC' cancels.  Dunno
whether this is a doc bug or the behavior (on Windows) is bugged.

5. Overall, it looks a bit like someone wrote `menu-bar-open',
`x-menu-bar-open', and `w32-menu-bar-open', and it was decided to
replace `tmm-menubar' as the binding of `f10'.  But I don't really see
the advantage, especially considering the lack of good doc.


In GNU Emacs 25.1.1 (x86_64-w64-mingw32)
 of 2016-09-17 built on LAPHROAIG
Windowing system distributor 'Microsoft Corp.', version 6.1.7601
Configured using:
 'configure --without-dbus --without-compress-install CFLAGS=-static'