File Source for switch

<?php
/**
* @version $Header$
* @package themes
* @subpackage functions
*/
/**
* Setup
*/
require_once( '../kernel/setup_inc.php' );
include_once( KERNEL_PKG_PATH.'BitBase.php' );
if (isset($_SERVER['HTTP_REFERER'])) {
$orig_url = $_SERVER['HTTP_REFERER'];
} else {
$orig_url = $bit_index;
}
if (isset($_GET['theme']) && $gBitSystem->getConfig('users_themes') == 'y'){
$new_theme = $_GET['theme'];
if(isset($gBitUser) && $gBitSystem->getConfig('users_preferences') == 'y' ) {
$gBitUser->storePreference('theme',$new_theme);
setcookie('bit-theme', '', time()-3600*24*30*12, $gBitSystem->getConfig('cookie_path'), $gBitSystem->getConfig('cookie_domain'));
} else {
setcookie('bit-theme', $new_theme, time()+3600*24*30*12, $gBitSystem->getConfig('cookie_path'), $gBitSystem->getConfig('cookie_domain'));
}
} else{
setcookie('bit-theme', '', time()-3600*24*30*12, $gBitSystem->getConfig('cookie_path'), $gBitSystem->getConfig('cookie_domain'));
}
header("location: $orig_url");
exit;
?>

Source for file switch_theme.php