User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Firefox/24.0 (Beta/Release) Build ID: 20130822154523 Steps to reproduce: It seems Firefox does not remember the spell checking dictionary language across sessions. STR: 1) Install a dictionary for a language different than the browser's language 2) In a text field, right-click and select the newly installed language (optional) Verify that the pref is set correctly 3) Exit and restart the browser (may need 2 restarts) 4) Check the language setting in the context menu Actual results: The language for spell checking gets reset to the browser's locale Expected results: The language chosen should persist across browser restarts

This affects Linux FF 28, still. I noticed this many many years ago and assumed that it would just get fixed, but it never did.

Hmm, okay, perhaps my case is slightly different. I haven't installed any other languages and FF never gets reset to my locale, it always chooses the wrong language. I'll open a new bug I guess.

Would see that different. FireFox, ThunderBird, and SeaMonkey do show same behaviour in this. In all my installations (of all 3 candidates, on different machines, on XP and W8), a restart (not a reload for AddIns) sets English as spell checking language. My local is German, some XPs are German recoveries, other do use a German SpeechPack - no differences to all this. Since I've to deal with more than 2 languages, preferring an other one than English, this behaviour indeed is a problem. And, to add this, I miss a button in menu line to quickly, even saving one click so often, switch between languages. «right click, move down, open sub menu, pick it» vs. «click button and click language» saves time an work. (A button, changing it's outfit showing active language might be dream of my wishes. And if not, one quick click informs about used language, not moving into a sub menu as now.) In an international world, this is to me urgent.

Still an issue in Fx 39 on Win8, with 2 spelling dictionaries involved. It always reverts back to the English dictionary.

(In reply to Eric March from comment #3) As of bug 967494, landed on Thunderbird 38 and soon to land on SeaMonkey, these two programs have new behaviour: The spell check language in spellchecker.dictionary does not change if the user chooses to spell check in a different language. Each new message will start off with the dictionary defined in the preference. So let's forget about Thunderbird and SeaMonkey, since this bug is about Firefox. In Firefox the preference value changes as the user changes the language via the context (right click) menu explicitly or as websites are visited. Firefox tries to derive the language from the website visited, with varying success. I visited the following websites https://bugzilla.mozilla.org/ http://www.fnac.com/ http://www.hostalpancheta.es/es/contactar.php and my preference was set to en-US, fr-modern and es-ES in turn. Currently the preference has absolutely no value, that's why it is not exposed on the user interface. However, in meta-bug 1073827 there is an interesting discussion of whether this behaviour should change.

Closing this bug as per bug 1073827, comment #33. If you want to reopen it, please present a reproducible test case.