I upgraded to FreeBSD 11.1 and Fluxbox 1.3.7, the bug remains, and makes localized "Fluxbox menu" - "Configure" menu unreadable. I tried to recompile Fluxbox without NLS support, but then window titles become unreadable. On the attached picture menus with truncated texts in Russian are a result of "[config]" menu item. I have "LANG=ru_RU.KOI8-R" in environment. I attached my ~/.fluxbox/menu file.