Index: includes/form.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/form.inc,v
retrieving revision 1.481
diff -u -p -r1.481 form.inc
--- includes/form.inc	31 Jul 2010 04:01:51 -0000	1.481
+++ includes/form.inc	14 Aug 2010 21:22:17 -0000
@@ -3082,7 +3082,9 @@ function theme_button($variables) {
  */
 function theme_image_button($variables) {
   $element = $variables['element'];
-  $element['#attributes']['type'] = 'submit';
+  if (empty($element['#attributes']['type'])) {
+    $element['#attributes']['type'] = 'image';
+  }
   $element['#attributes']['name'] = $element['#name'];
   if (!empty($element['#value'])) {
     $element['#attributes']['value'] = $element['#value'];