Index: admin_theme.module
===================================================================
--- admin_theme.module	(revision 372)
+++ admin_theme.module	(working copy)
@@ -134,6 +134,11 @@ function admin_theme_init() {
     }
   }
   
+  
+  if ($_POST && isset($_POST['op']) && strtolower($_POST['op']) == 'preview') {
+  	$admin_theme_disallow = TRUE;
+  }
+  
   // we should not show the admin theme if the user has no access or the path is in the disallow list
   if (!user_access('access admin theme') || $admin_theme_disallow) {
     unset($GLOBALS['custom_theme']);