Index: wp-includes/admin-bar.php
===================================================================
--- wp-includes/admin-bar.php	(revision 19159)
+++ wp-includes/admin-bar.php	(working copy)
@@ -631,7 +631,8 @@
 		'title' => $form,
 		'href'  => '#',
 		'meta'  => array(
-			'class'   => 'admin-bar-search'
+			'class'   => 'admin-bar-search',
+			'onclick' => 'return false;'
 		)
 	) );
 }