When using themes you want to changes some of the translations specifically to the theme while keeping the standard translations for most of the text. Duplicating the main translation file is a headache for maintainance. This how to provides a solution.
The number of languages supported by the standard CJuiDatePicker implementation is limited and the language code to use is different from the application's language code. This Wiki shows how to improve on that.
Sometimes you want to use exisiting translations for locales, which do not directly match. An example would be a website targeting Germany (de_de), Austria (de_at) and Switzerland (de_ch, fr_ch, it_ch). Although you may have exisiting translations for German (de), French (fr) and Italian (it), there are problems using it directly.
Your application is international and you have to select the best language for the user. Your user may have selected 'fr_CA' and you have 'fr_FR' or 'fr' available. What do you do? Here is a tip.