Date literals ("Oct", "October") are not using localization.

Here's the fix:

• Change the print_date() function in date_api.php from using date() to using strftime() which supports localization. The problem here is that the date format syntax is different from the date() function, so the config files need to change. See: http://php.net/strftime

• Add the locale string in the config -- or better, in the language file. (Swedish is either "swedish" or "sv-SE" for example).

• Add a setlocale() call at the top of the print_date() function, or in some init function.

• Now you just have to change all instances of date() where it's used to print out the date to print_date().
  (Mantis own print_date() is not used used consistently throughout Mantis, the regular date() is used a lot too!)

Approximate time to fix this bug: 12 min. :)