Root had no support for special characters see the output of `locale` for information about current localization. Undo all changes for xorg and `dpkg-reconfigure locales` and choosing the appropriate locale, in my case de_CH.UTF-8 fixed the problem, too! Due negative experiences with choosing anything else than "C - No Localization" in debian installation process, I selected C as default localization during installation. The problem was most programs just support ASCII so you had to be careful with ISO-8859-1 or UTF-8 and writing configuration files. Once I believed my system was broken as a novice. I'm not sure if this can also happen with UTF-8 because it should have an approximate backward compatibility with ASCII.