After last Firebug update all labels get translated to French but I didn’t ask about it. And I really can’t get rid of that. I am in France now, but all my locales, all preferences are set to English (Great Britain), only timezone is set to (UTC+01:00) Brussels, Copenhagen, Madrid, Paris. At the same time I have English version of the Firefox.
P.S. It really drives me crazy. Does anybody know how to force Firebug to use only English and never translate to any other language?
It is fixed now. In fact, I did nothing. I had 10.0.3 (ESR) version of FireFox. After I updated to 10.0.6 the bug disappears. Firebug version remains the same 1.9.2.