I've decided that displaying the validation error message in the repeat region is too complicated. I've gone with the simpler approach of having a message box for failure show at the top of the page.
Problem is when the validation error triggers, it does not reset when the user refreshes the page or clicks on any button in the nav bar and goes back to the page. I can even close the browser and reopen it to the same page. The validation error message displays. If I click the "add to cart" button and select a dress size, the validation error is reset and the page goes to the cart.
How do I reset the session variable that holds the trigger for the validation error in case the user clicks on another link or closes their browser?
You can view the problem by going to spring.php, and clicking add to cart without selecting an option. Then reload the page or click on another link. When you go back to the page, the validation error is not cleared from the previous attempt.