RE: C-M-TAB stand-in for M-TAB, on MS Windows?

[Drew Adams]

> >> M-TAB doesn't work on MS Windows. ESC TAB works in its 
> >> stead in some contexts, but not all.
> > 
> > FWIW, on NT derived systems one can use the function 
> > `w32-register-hot-key' to enable Emacs to see M-TAB 
> > (untested on Vista).
> 
> On what version did you test this?

It seems to work on this version:

GNU Emacs 23.0.60.1 (i386-mingw-nt5.1.2600)
 of 2008-05-04 on LENNART-69DE564

However, the doc string is not as clear as it could be:

 Register key as a hot-key combination.
 Certain key combinations like Alt-Tab are reserved for system use on
 Windows, and therefore are normally intercepted by the system.  However,
 most of these key combinations can be received by registering them as
 hot-keys, overriding their special meaning.

 key must be a one element key definition in vector form that would be
 acceptable to `define-key' (e.g. [A-tab] for Alt-Tab).  The meta
 modifier is interpreted as Alt if `w32-alt-is-meta' is t, and hyper
 is always interpreted as the Windows modifier keys.

 The return value is the hotkey-id if registered, otherwise nil.

By default, `w32-alt-is-meta' is t. I tried (w32-register-hot-key [A-tab]) on
Windows XP, and it had no effect. However, I then tried (w32-register-hot-key
[M-tab]), and it worked.

I can't tell from the doc string whether registering [A-tab] should have an
effect, in which case there is a bug, or not.

Also, why must KEY be "a one element key definition in vector form"? Just
curious. What is the underlying restriction?

Questions:

1. How to UNregister a hot key, once it's registered?
2. How about registering M-tab by default?
3. How about mentioning w32-register-hot-key in the Emacs manual,
   and indexing it there? This represents an important FAQ.
4. Likewise, for the Elisp manual.
5. Likewise, for NEWS. How are users supposed to know about this?