backward_compatibility with currentIndex

AdminController.php

<?php
/**
* 2007-2014 PrestaShop
*
* NOTICE OF LICENSE
*
* This source file is subject to the Open Software License (OSL 3.0)
* that is bundled with this package in the file LICENSE.txt.
* It is also available through the world-wide-web at this URL:
* http://opensource.org/licenses/osl-3.0.php
* If you did not receive a copy of the license and are unable to
* obtain it through the world-wide-web, please send an email
* to license@prestashop.com so we can send you a copy immediately.
*
* DISCLAIMER
*
* Do not edit or add to this file if you wish to upgrade PrestaShop to newer
* versions in the future. If you wish to customize PrestaShop for your
* needs please refer to http://www.prestashop.com for more information.
*
*  @author    PrestaShop SA <contact@prestashop.com>
*  @copyright 2007-2014 PrestaShop SA
*  @license   http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
*  International Registered Trademark & Property of PrestaShop SA
*/

class AdminController
{
    public static $currentIndex;
}
global $currentIndex;
if (isset($currentIndex)) {
    AdminController::$currentIndex = $currentIndex;
}

Add this to backward.php

/* Get out if the context is already defined */
if (!in_array('AdminController', get_declared_classes())) {
    require_once(dirname(__FILE__).'/AdminController.php');
}