Thanks to reply.

Disabling ibus did the trick.

Before that I tried to change the $LANG variable like the emacs wiki recommend[0] but without success.

Just in case, I also tried to run `emacs -nw' and it works correctly even if I enable the ibus support in sakura[1].

I will for the moment remove ibus from my system as I don't need it.

[0] "Another solution is to change the language locale suffix to large letters, e.g., from LANG=nb_NO.utf8 to LANG=nb_NO.UTF-8." http://www.emacswiki.org/emacs/DeadKeys

[1] http://www.pleyades.net/david/projects/sakura

2013/8/20 Stefan Monnier <monnier@iro.umontreal.ca>

> I encounter an odd behavior using emacs under Linux. When I type a dead
> key like ~ (dead-tilde) or ` (dead-grave) I get the error "<dead-tilde
> is undefined>" (where dead-tilde is the name of the dead chars).

We've had various reports of such problems, in the past.
Yours sounds like it's related to http://debbugs.gnu.org/14044 can you
look at this thread and see if it might help you track down the source
of the problem?

> value of $LANG: fr_CH.utf8
> value of $XMODIFIERS: @im=ibus

It sounds like a bad interaction with ibus.
Does someone know what might be going on with ibus?

Stefan