I don't know if this is possible, but as I mentioned in another issue, you said it's not really possible to remove the item/user from the right-hand column once it's been added to the left one. Another way around this would be to have the items/users moved from the right to the left, highlighted in the right column, so it's obvious which ones have already been added to the left columns!
I don't know if this is possible, but as I mentioned in another issue, you said it's not really possible to remove the item/user from the right-hand column once it's been added to the left one. Another way around this would be to have the items/users moved from the right to the left, highlighted in the right column, so it's obvious which ones have already been added to the left columns!