Index: sites/all/modules/privatemsg/privatemsg-list.js
===================================================================
--- sites/all/modules/privatemsg/privatemsg-list.js	(revision 4696)
+++ sites/all/modules/privatemsg/privatemsg-list.js	(working copy)
@@ -1,3 +1,3 @@
 Drupal.behaviors.hideButtons = function (context) {
- $("input.privatemsg-action-button").hide();
+ $("div.privatemsg-op-button").hide();
 };
\ No newline at end of file
Index: sites/all/modules/privatemsg/privatemsg.module
===================================================================
--- sites/all/modules/privatemsg/privatemsg.module	(revision 4696)
+++ sites/all/modules/privatemsg/privatemsg.module	(working copy)
@@ -1915,6 +1915,8 @@
       '#attributes'    => array('onchange' => "$('#edit-submit').click()"),
   );
   $form['submit'] = array(
+      '#prefix'     => '<div class="privatemsg-op-button">',
+      '#suffix'    => '</div>',
       '#type'       => 'submit',
       '#value'      => t('Execute'),
       '#submit'     => array('privatemsg_list_submit'),