- Patch #104280 by dww: node_form_add_preview() broken if you alter the Preview button at all.

modules/node/node.module

@@ -2045,7 +2045,7 @@ function node_form_add_preview($form) {
   global $form_values;
 
   $op = isset($form_values['op']) ? $form_values['op'] : '';
-  if ($op == $form_values['preview']) {
+  if ($op == t('Preview')) {
     drupal_validate_form($form['form_id']['#value'], $form);
     if (!form_get_errors()) {
       // We pass the global $form_values here to preserve changes made during form validation