The Firefox web browser is available in dozens of languages that you can download from the official Languages page over at the Mozilla website. Sometimes you may want to have two different interface languages available, either for testing purposes, because the wrong language version of Firefox was downloaded, or because users with different language backgrounds are working with the browser.
That's why Mozilla is making available language packs for Firefox that users of the browser can install just like add-ons. Once installed it is possible to switch between all interface languages in the browser without having to install multiple different versions of Firefox.
A language pack should not be confused with dictionaries. The former changes the language of menus and interface elements in the browser, the second adds spell checking options for that language to Firefox.
Mozilla announced this Friday that auto-updating language packs are now available. What that means? The people responsible for maintaining the language packs had to release a new pack for every Firefox version that was released by Mozilla. Historically, this has taken some time before they became available for users to download.
The auto-update feature fetches the language packs automatically during the Firefox build process so that they become available at the same time Firefox itself is updated. This means that Firefox users won't run into compatibility issues with their installed language packs anymore which was previously the case if a language update was not available at the time of a new Firefox release.
The new methodology also means that new languages - Mozilla says dozens - become available for the first time as separate downloads and that existing but inactive language packs will receive updates again.
Selecting a different interface language in Firefox can be done either by editing a value in the browser's about:config dialog or by installing an add-on like Quick Locale Switcher which should be the better option in most situations.
To change the language manually do the following:
- Type about:config into the Firefox address bar and hit enter
- Say you will be careful if it is your first time
- Search for the term general.useragent.locale
- Double-click it and change its value to the short code of the language you want to use
- Restart the browser
Since it is required to do so every time you want to change the language, it should be clear that using the extension is the better option. (via Sören)