Use submit button to trigger validation and prompt to save instead of submit action

I want to add a Submit Button that will trigger all validation using the built-in feature. This will also work well with the "forms validation" setting done on the form properties. See snapshot below.

However, if the validation is successful, I want to prompt for the save dialogue box instead actually submitting the form using this line of code:

app.execMenuItem("SaveAs");

How is this possible?

Tarek