How to get firefox language setting? (REALLY)

Question

I know this question has been answered before, but the answer given is not the complete story:

I went into Firefox's Options->Content and removed all languages except German/Germany, and navigator.language hasn't changed - it's still en-GB (I'm in the UK).

I'm told if I get the German Firefox INSTALL it will work, but I shouldn't need to do that, right?

The useragent string still contains en-GB, too; but the accept-language on HTTP headers IS set correctly. So this seems to be a bug in Firefox, I spent a bit of time wading through their bugzilla, but I can't see this exact bug logged, though to me it seems a pretty huge oversight?

Answer 1

Both navigator.language and the HTTP User-Agent header use the value of the preference "general.useragent.locale", which is hard-coded in intl.properties to the locale of the Firefox build you downloaded: http://mxr.mozilla.org/mozilla-central/source/toolkit/locales/en-US/chrome/global/intl.properties#8

Or for your en-GB build: http://hg.mozilla.org/l10n-central/en-GB/file/88dd673c01f1/toolkit/chrome/global/intl.properties#l8

If you'd like to change it for your build, just load about:config, find general.useragent.locale, double-click it, and change the value.

Answer 2

I would recommend to use a Firefox Add-on for this task. Simple Locale Switcher, Locale Switcher or Quick Locale Switcher etc. (* Caution some of this Add-ons may contain ad ware or may not work if you've just updated firefox).

*Another solution is to download a different old firefox version using the language/locale. (Caution) You need and install it in a different folder so you won't overwrite your existing version. Download here I'm using firefox 28 in Spanish. I disabled updates and I rejected using it as my default browser. Only one firefox version should be running at the same time if you do this.