bug#30010: 25.3; changing layout in Windows 8.1 causes endless scroll in echo-area

[martin rudalics <rudalics@gmx.at>]

 >> Couldn't we tell users how to prevent Emacs from fiddling with such
 >> key bindings?
 >
 > I thought about mentioning this in PROBLEMS, but it sounded too
 > obscure even for that.  I could be convinced, though.  Did you mean
 > PROBLEMS or did you mean something else?

It looks to me as if now on Windows (1) Emacs grasps key combinations
before anyone else gets hold of them and (2) if it doesn't find an
appropriate binding for them, emit a warning unless it's a combination
reserved for Windows itself.  For example, on XP I use ahk to emulate
the Aero combination of

lwindow key + left key

via

ctrl + lwindow + alt + left key

This works with all other applications and also in a "normal" emacs
where I assign

(setq w32-lwindow-modifier 'hyper)	; lwindow is hyper

But with emacs -Q I get the warning

<C-M-lwindow> is undefined

although I apparently don't get it in later invocations of the same
executable.  I think (2) is a bad idea and there should be an option
to turn off such warnings.  Unfortunately, I have not been able to
understand how this mechanism works nowadays.

martin