#195540 by hass: fix XHTML validity with disabled checkbox in locales form

includes/locale.inc

@@ -71,7 +71,7 @@ function theme_locale_languages_overview_form($form) {
     if (is_array($element) && element_child($key)) {
       // Disable checkbox for the default language, because it cannot be disabled.
       if ($key == $default->language) {
-        $form['enabled'][$key]['#attributes']['disabled'] = TRUE;
+        $form['enabled'][$key]['#attributes']['disabled'] = 'disabled';
       }
       $rows[] = array(
         array('data' => drupal_render($form['enabled'][$key]), 'align' => 'center'),