Plugin Request A GUI Item Sell/Shop Plugin

On timeless PVP if you do /shop, you get a gui and you can buy things or sell things.. The thing i am most intrested in is the selling mehanism. When you click sell you are greeted with a box and you drag all your unwanted items in there, then you click sell and it tells you how much you will get and then you get the money...

Why this?
because it is a lot more simple and easier to sell items, then you would have to sell them 1 by 1.

Hope you understand what I am asking

Thanks
~Endy