Discount Code fixed amount discount

I have been using your excellent discount code add-on for some time with % discounts and all is good.

However if I offer a fixed amount discount (which is a feature of this add-on) and the customer orders items less than that value then the order total ends up less than zero (=<0). I only have paypal as a payment module and when checking out the customer gets a paypal error. Paypal obviously can't process a negative vaule but should that happen with this add-on? In this instance shouldn't the payment module be skipped and order success registered anyway when the order total is =<0?

I think 2.2.0 will not process any payment module if the value is 0. A negative number in checkout is just wrong.

I have looked into some more threads and the ones regarding using the discount addon for gift vouchers is interesting. In that instance you would want a negative value to update the code balance if a customer had only used part of the discount value.
In 2.2.0 will the order register as a success if the value is 0 and the payment module is not processed? I haven't updated to that yet.

Discount codes does not support vouchers but it's on the todo list.

In case of a voucher the summary would look like this:

Subtotal: 100
Tax: 10
Voucher: -110
Payment Due: 0

Appreciated. Of course, that's how it should be, but I was thinking as a short term fix I could manually update any code with an outstanding balance as long as the customer can get order success if it happens that the value is =<0. The only reason there could be for that value is a discount, in which case the customer has already paid or received a gift. It wouldn't be large volumes to action.
Thanks for the prompt replies.

The file you would have to modify in order not to run the payment module on negative anounts is pages/order_process.inc.php.

Other than that. Vouchers is on the wishlist. :)