GTK programs (like Firefox and Gedit) can’t properly handle the special characters of Esperanto alphabet (Latin-3) like ĉ or ŭ. It beeps when you try to do the ^+c combination, for instance, although you are yet able to type this letter in another program, even in Terminal.

I use Firefox in KDE and I did exactly what FLOSS & Cia suggested. Simply add to the file /etc/environment

the following line:

GTK_IM_MODULE=xim

Explanation for this trick may be found here.

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