Product Still remains in my Shopping Cart when I click on Cancel in Pay Pay. Why?

Why does the Shopping Cart in Market Press continue to have the product in it when you press "Cancel" in Pay Pal?

I would think the cart would be empty instead. So when a customer clicks on "Cancel" in Pay Pal for whatever reason, then once my customer returns back to my website, they have to go back into my Shopping Cart and Click on empty to get rid of the product if they want to start over again? Seems though the cart would alreadybe empty for them. Why make the customer empty the cart when the order is canceled?