Implements template_preprocess_HOOK() for overlay.tpl.php
If the current page request is inside the overlay, add appropriate classes to the <body> element, and simplify the page title.
function template_preprocess_overlay(&$variables) {
$variables['tabs'] = menu_primary_local_tasks();
$variables['title'] = drupal_get_title();
$variables['disable_overlay'] = overlay_disable_message();
$variables['content_attributes_array']['class'][] = 'clearfix';
}