bug#14661: 24.3.50; `C-<scroll>' is seen as `C-<pause>'

[Eli Zaretskii <eliz@gnu.org>]

> Date: Tue, 18 Jun 2013 19:53:02 -0700 (PDT)
> From: Drew Adams <drew.adams@oracle.com>
> 
> Dunno whether this is an Emacs bug or a keyboard problem.

Neither.

> When I use `C-h k' and then press Control and hit the Scroll Lock key,
> Emacs takes that as `C-<pause>', not `C-<scroll>'.  However, every other
> combination of a modifier with the Scroll Lock key, and use of no
> modifier with it, acts as I would expect: Emacs sees
> `<scroll>',`M-<scroll>', `C-M-<scroll>', `C-S-<scroll>', `S-<scroll>',
> `M-S-<scroll>', and `C-M-S-<scroll>'.

This is a conundrum whose way out I don't know, nor whether it at all
exists.  Windows gives us the same virtual key code VK_CANCEL for both
C-<scroll> and C-<pause> (for reasons of backward compatibility).  We
want to produce a "normal" Ctrl-modified key from this, but we don't
know which one of the two was pressed.  So we arbitrarily choose to
produce C-<pause>.

If someone has a way out of this that doesn't require a complete
rewrite of the keyboard reading code, please speak up.  Otherwise,
this will remain a very distant wishlist.