How to remove/disable the 'language neutral' option in Drupal ?

In: i18n.module in the i18n module directory, change the following function:


function i18n_node_language_list($node, $translate = FALSE) {
// Check if the node module manages its own language list.
$languages = node_invoke($node, 'language_list', $translate);
if (!$languages) {
if (variable_get('i18n_node_'. $node->type, 0) >= LANGUAGE_SUPPORT_EXTENDED) {
$languages = locale_language_list('name', TRUE); // All defined languages
}
else {
$languages = locale_language_list(); // All enabled languages
}
if ($translate && isset($node->tnid) && $node->tnid && ($translations = translation_node_get_translations($node->tnid))) {
unset($translations[$node->language]);
foreach (array_keys($translations) as $langcode) {
unset($languages[$langcode]);
}
}

// HACK - get language neutral away
//$languages = array('' => t('Language neutral')) + $languages;

}

return $languages;
}