Re: Emacs doesn't set mark with C-<SPC> anymore after Xubuntu upgrade to 14.04

[Bob Proulx]

Timothée Flutre wrote:
> To investigate this, I opened a terminal (xfce4-terminal 0.6.3), launched
> emacs inside it (emacs -nw), wrote a few dummy lines in *scratch* and
> ...
> On StackOverflow, I learned that C-<SPC> was not working likely due to the
> fact that the terminal emulator wasn't properly transmitting C-<SPC> to
> emacs (http://stackoverflow.com/a/16271042/597069).

I installed xfce4-terminal 0.6.3 on my Debian system.  I launched it.
I started emacs within it just as you have indicated.  For me C-SPC
works fine and I can set the mark using it.

This leads me to believe that for some reason your xfce4-terminal does
something different that is problematic for you.  I don't know the
answer but I would concentrate on the question of why your
xfce4-terminal does not pass C-SPC through as C-@.

  C-h c
  Describe key (or click or menu item):
  C-spacebar
  C-@ runs the command set-mark-command

Therefore I conclude that your xfce4-terminal should be doing the same
but does not.

There are many ways things might fail and therefore hard to
immediately diagnose why it isn't working.  I would try another
terminal emulator and see if it functions better.  I would try looking
at xmodmap to see if you have a customization that is remapping the
keyboard.  I would try xev to verify that control is sending Control_L
and that spacebar is sending a "space".  I would see if there is an
XFCE customization that might be affecting things.

I might try temporarily creating a pristine new user "guest42" or some
such and log in there just to verify the behavior with a pristine new
environment.  If it works there then you have confirmed that the
problem is in your normal environment somewhere.  You can delete the
temporary user account after you have completed testing with it.

I am sure there are many ways to debug this problem.

Bob