We're developing an example ARIA spin button, and we're hoping for a clarification around aria-valuenow.

From the APG:

"The slider element has the aria-valuenow property set to a decimal value representing the current value of the slider."

What should the value of aria-valuenow should be when a user (for example) pastes in some invalid input. Should aria-valuenow simply not change? Should it be set back to some default when the spinbutton loses focus? Should the paste be undone by reverting to the previous value?

Thanks!