Index: themes/seven/style.css
===================================================================
RCS file: /cvs/drupal/drupal/themes/seven/style.css,v
retrieving revision 1.38
diff -u -r1.38 style.css
--- themes/seven/style.css	22 Dec 2009 19:45:00 -0000	1.38
+++ themes/seven/style.css	2 Jan 2010 19:58:19 -0000
@@ -823,6 +823,7 @@
   padding-right: 20px;
 }
 body.in-maintenance #page {
+  overflow: auto;
   width: 770px;
   margin: 0 auto;
   padding-top: 2em;
Index: modules/overlay/overlay.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/overlay/overlay.module,v
retrieving revision 1.4
diff -u -r1.4 overlay.module
--- modules/overlay/overlay.module	14 Dec 2009 16:36:56 -0000	1.4
+++ modules/overlay/overlay.module	2 Jan 2010 19:58:19 -0000
@@ -259,6 +259,21 @@
 }
 
 /**
+ * Preprocess template variables for maintenance-page.tpl.php.
+ *
+ * If the current page request is inside the overlay, add appropriate classes
+ * to the <body> element.
+ *
+ * @see overlay_get_mode()
+ */
+function overlay_preprocess_maintenance_page(&$variables) {
+  if (overlay_get_mode() == 'child') {
+    // Add overlay class, so themes can react to being displayed in the overlay.
+    $variables['classes_array'][] = 'overlay';
+  }
+}
+
+/**
  * Preprocess template variables for page.tpl.php.
  *
  * Display breadcrumbs correctly inside the overlay.
