Comment 17 for bug 335732

I'm seeing this too.
It happens when I activate iBus in the language preferences.

I've read that it has something to do with iBus not supporting dead keys:
http://ubuntuforums.org/archive/index.php/t-1404209.html

I've tried the workaround described there, to do "unset XMODIFIERS" before launching the application where I have problems, specifically the infamous Skype. Doing that allows me to write accented letters using the dead keys as before, but I can't use iBus any more in that application.

The problem also happens with Emacs which is a more serious issue for me, although Emacs has its own input methods which I used before installing iBus, so I'll unset the XMODIFIERS also for it. At least everything works fine in Firefox.