Improvement to Gift Certificates

We recently had a customer request to set the balance of a gift certificate to $0.00 for one of their users. When I tried, I was presented with a message stating that the balance must be greater than 0. I can understand why you would add that logic when adding a gift certificate, but when managing a gift certificate, we should be able to set the balance to 0, if needed.

We don't want to delete the gift certificate, because we are using them effectively as credit cards on this site, so we don't want to have to issue a new one later on.

Please add the ability to set the balance of gift certificates to 0, if adjusting one after it is created.