Dojo Forum

Hi, I am new to DoJo (just picked up a book and start coding couple of days ago), so forgive my ignorance. My question is, if I am using dijit.form.FilteringSelect and I want on the fly validation (like if user inputs something that is not in the list), is there a way to set one of the options as invalid choice? Here is the example of what I am talking about:
Lets say we have following:

1 > Select One
2 > Option A
3 > Option B

I want initially show user SelectOne, so they don't blindly move on, but I want to prevent them from moving on if SelectOne is still selected...

Thanks a bunch...