Canceled invoices

It would be nice if when we change the status of an invoice to "cancelled" the remaining balance automatically 0s out and will save as such. As of right now, if we cancel an invoice, the invoice goes to the "paid" section of the invoices page which is great, but the dash board widget will still include them in the "unpaid invoices" count which we do not want. But if I go back and switch the remaining balance to 0 and keep the status as "cancelled", when I save it...it automatically switches the status to "paid" which defeats the purpose of using the "cancelled" status. This fix will be good because then we can see what bills have been paid for with a payment or which have been cancelled by us with out having to go into every invoice.