Binder need to communicate it state changes (i.e. readonly)

[dirkey]

Describe your motivation

The binder support to change all fields from readonly and back. If you build up complex forms with custom subcomponents, the binder does not support notifications (listener) if the readonly state is change. The developer is forced to implement a solution on top of the binder. It is easier to use the binder as the readonly state of a form.

Describe the solution you'd like

The Binder just need a registration for listener, if the readonly state is changed. A developer is able to implement this listener into his components and register them to the binder.

Additional context

Currently, the binder is very calm about it states. If you need to implement functionality for complex forms, you are force to build it around the binder. Even if binder hold all states. Each more abstract implementation of handling complex forms is impossible with the Binder. Currently, i use an own subclass of the Binder.