Implements hook_preprocess_html().
If the current page request is inside the overlay, add appropriate classes to the <body> element, and simplify the page title.
function overlay_preprocess_html(&$variables) {
if (overlay_get_mode() == 'child') {
// Add overlay class, so themes can react to being displayed in the overlay.
$variables['classes_array'][] = 'overlay';
}
}