Please describe the problem:
I'm using Ubuntu edgy with pretty much the default Gnome setup, with
exceptions noted below.  I use typical x86 PCs whose keyboards contain
a "Windows" key.

I'm one of those people who uses Emacs all the time.  And one of the
key sequences I often type is C-M-SPC (that is, I hold down the
Control and Alt keys, and then hit the Space bar).  But Emacs acts
exactly as if I'd typed M-SPC, which alas does something different.
(Specifically: you can type C-h l to make Emacs display the last
couple dozen keyboard events it's received; it shows ESC SPC in both
cases).

This happens with both a totally virgin setup, as well as my
somewhat-customized setup.  By "totally virgin", I mean that I became
root, created a new user with "adduser", logged in as that user via
gdm, started gnome-terminal, and typed "/usr/bin/emacs -nw -q
--no-site-file".  By "my somewhat-customized setup", I mean that I've
disabled menu accelerators in gnome-terminal.

I've also noted that urxvt doesn't have this problem.

Is this a bug?  In any case, is there some way I can get Emacs to
"hear" C-M-SPC?


Steps to reproduce:
1. start gnome-terminal
2. type /usr/bin/emacs -nw -q --no-site-file
3. in Emacs, type C-h c C-M-SPC


Actual results:
Emacs prints "M-SPC runs the command just-one-space", or perhaps "ESC SPC runs the command just-one-space", which for my purposes are equivalent

Expected results:
Emacs prints "C-M-@ runs the mark-sexp"

Does this happen every time?
yes

Other information: