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.

For instance, in isearch, C-s foo ESC TAB does not do what C-s foo M-TAB does,
which is isearch-complete(-edit). Instead, it exits isearch and calls
`complete-symbol'.

Some Windows users change the Meta key to something other than ALT, but that is
an individual solution and preference. It would be good to have a default
binding on Windows that works generally.

C-M-tab is undefined by default, and many (most? nearly all?) users on Windows
will use Emacs with the window manager, so this key is available to them. What
about, on Windows, binding C-M-tab to whatever M-TAB is bound to? To me, this
seems like a good fit. (No reason to unbind M-TAB; it's enough to add C-M-tab.)

If this doesn't sound like something you find appealing, then drop it - I don't
feel like discussing this to death.

[It seems like this would have been discussed already, but I didn't find
anything specifically about it in the archives. There was a 2005 thread ("M-Tab
on w332 (and other window systems?)") about possibly binding C-RET in place of
M-TAB on Windows, but that was rightfully rejected because C-RET is used for
other things.]