Can I simply change the LANG environment variable for one program?
No, don’t do that! All desktop applications must use the same UTF-8 setting. You may change LANG from “de_DE” to “en_US” or from “de_DE.UTF-8” to “en_US.UTF-8”, but not from “de_DE” to “de_DE.UTF-8”. If you want to change the UTF-8 usage, log in as root (or Administrator), change the setting globally — i.e. in /etc/sysconfig/i18n — and reboot the system. If the desktop delivers not-UTF-8 encoded data and an application expects UTF-8 encoded data (or vice versa) there is a wide variety of results: unknown keyboard bindings, application crashes…
