How are you supposed to use the Add button for Post Function create/edit views?

I am trying to work out a create view for my post function and referring to this documentation for methods. There is an Add button at the bottom of the page. This is surely great for submitting and I figured out that pressing it will emit an event (which is nowhere documented) that I can listen to with the AP.events function and then trigger the validation/saving. However, pressing on it will redirect me to the transition overview page, no matter if the configuration of the post function is valid or not.

Has somebody figured out how I can prevent leaving the page if validation fails? using my own button certainly is not a very user-friendly solution…