Open a sales order and go to payment tab.
Select any credit card there and edit it, the billing address does not copy the customer billing address. Have to enter the address manually, but with the credit card screen opened, can't open any other screen, so can't go to customer to see the billing address.
A button like "use default billing address" will be really nice.
Steps to reproduce:
Read more at http://www.xtuple.org/mantis/view.php?id=5441