Ability to pass other properties into the form other than initialValues

feature request

Is it possible to allow a way to inject other properties into the form. Right now there is only initialValues. For example, in my use case I want to pass in a callback that a button within the form will be mapped to. The only way I can do that is if I hack that as part of the initialValue property. Now there is no separation between what is the initial value of the form values vs other attributes such as actions.

Thanks,
Derek