Rather than using the form validation to revert changes, is it possible to cancel or revert the changes to the original value on the "User input of a field" event rather than waiting until they're done and doing it.

e.g. you have an order that has multiple line items with their own delivery date. Some items have already shipped while others are still awaiting dispatch. The user goes in and updates the quantity of some items, one or more of which have already shipped. So as we can't disable individual rows, we need to prevent the user from making the change in the first place rather than reverting the changes on validation. As it is something they need to know when they're making the change.  It could also be that they're trying to select a value where there isn't enough stock for the updated value.