Support for usecase "submit button of form in navbar"

A common UI pattern in iOS consists in putting the submit button of a form into the right navbar corner. I wonder how to implement this with this library. The submit button handler would need the local state of the form component in order to submit the form. This is not feasible when using `overlayComponent` and `component`.
The only -- awkward -- way I can imagine doing this is storing the local form state in a flux store, making it visible across components. Any ideas?