Be able to edit/amend a printed invoice raised from Invoicing Module

At the moment once you print invoices from the invoicing module the then become locked down so no editing is possible. Would be great if this wasn't the case as clients raise and print invoices and realise a spelling/pricing mistake, get told to change something by management and have to cancel the invoice and raise a new one to apply the change Wouldn't it be easier to allow changes to be made instead of having to cancel the invoice completely to change a small mistake?