Block Layered Price Slider - Use "Unit Price" // Prestashop - repost

Hi ! This is a small and quick development project. Specifications : - Prestashop Plateform 1.5.4.1 - Few modifications (JS , PHP and SQL) Explication : i have to manage unit price in my prestashop website. i need to manage in the category page (product-list) the unit price of prestashop. In fact, I have a problem with the field "sort by". I display my products using the unit price (price depends by square meters). When I want to display my products by price asc or desc, my products are classified with the sales price but not with the unit price. I know that is the classic behavior of prestashop but when i want to manage product with unit price, this behavior is not good in my case. i want to sort products depend by unit price and not by sales price with this field ! The devellopement of this feature depend from a piece of code from a prestashop forum : [login to view URL] Contact me if you want more explication Regards,