Sets the value of the user register and profile forms' langcode element.
function _user_language_selector_langcode_value($element, $input, &$form_state) {
// Only add to the description if the form element have a description.
if (isset($form_state['complete_form']['language']['preferred_langcode']['#description'])) {
$form_state['complete_form']['language']['preferred_langcode']['#description'] .= ' ' . t("This is also assumed to be the primary language of this account's profile information.");
}
return $form_state['values']['preferred_langcode'];
}