The register_translation function in languages.php register all translations, even

if they are not registered for the core-system.

But you can't access such languages.

Example :

For the core-system you have languages-files for EN, DE, FR.

A plugin that you want to us comes with languages-files for EN, DE, FR, PL, ES, NL, XX.

So all this languages will be registered and added to the translation-array. But there is not possibility for the user to access PL, ES, NL, XX.

A small patch will fixe this :

The original function is :

 /**
  * When given a full path, finds translation files and loads them
  *
  * @param string $path Full path
  */

  function register_translations($path) {
   global $CONFIG;
   
   if (isset($CONFIG->debug) && $CONFIG->debug == true) error_log("Translations loaded from : $path");
   
   if ($handle = opendir($path)) {
    while ($language = readdir($handle)) {
     if (!in_array($language,array('.','..','.svn','CVS', '.DS_Store', 'Thumbs.db',)) && !is_dir($path . $language)) {
      @include($path . $language);
     }
    }
   }
   else
    error_log("Missing translation path $path");
  }
  

This should be replaced with :

 /**
  * When given a full path, finds translation files and loads them
  *
  * @param string $path Full path
  * @param boolean $core Core-translation or Plugin-translation
  */
  function register_translations($path, $core = false) 
  {
  
   global $CONFIG;
   
   if (isset($CONFIG->debug) && $CONFIG->debug == true) error_log("Translations loaded from : $path");
   
            if ($core == TRUE) {            
                // All core-languages should be registered
                if ($handle = opendir($path)) {
                    while ($language = readdir($handle)) {
                        if (!in_array($language,array('.','..','.svn','CVS', '.DS_Store', 'Thumbs.db',)) && !is_dir($path . $language)) {
                            @include($path . $language);
                        }
                    }
    } else {
     error_log("Missing translation path $path");
    }
   } else {
                // Only register those plugin languages, wich are alreday registerd in core,
                // because there is no possibility to use an other language
                $languages = get_installed_translations();
                foreach ($languages AS $languageKey => $languageName) {
                    if (is_file($path . $languageKey . '.php')) {
                         @include($path . $languageKey . '.php');
                    }
                }
   }
   
  }

And in the last line of languages.php add a TRUE to the registration of the core-languages

  register_translations(dirname(dirname(dirname(__FILE__))) . "/languages/", TRUE);