Although I picked the xfce4-panel as the culprit, the problem affects other components too: when the `LANG` is set to, for example, `uk_UA.KOI8-U` various labels and other textual entries get messed up badly. Many, but not _all_. For example, the title of main application menu (called "Applications" in English), shows junk characters instead of Ukrainian "Програми" -- bad. However, in the popup menu itself, the entries are still listed in proper Cyrillic. This seems like a 4.18 regression -- I still have 4.16 installed on a different machine, and everything looks good there. Changing `LANG` to `uk_UA.UTF-8` fixes the problem, but I'd rather stick to the 8-bit encoding... It feels related to the earlier [bug 12294](https://bugzilla.xfce.org/show_bug.cgi?id=12294), but on a much greater scale :disappointed: