I'm trying to edit an existing program that has an inventory list and a shopping cart list. The shopping cart list begins empty, and as you select items from the inventory list on the left, they are added to the shopping cart on the right. The original program was designed to use with a mouse and double-click to add/delete method. I'm just trying to edit the code so that there will be arrows to scroll up and down the lists, as well as left and right to go between the two lists, so the user has to use an add/delete button. I think I've got the scroll up and down working, but I am stuck trying to figure out how to go back and forth between the two lists.
Any help would be appreciated