When added to a page within a Form, it will disable all the fields of the form and make them read only. Also it will disable the Submit button on the page.
The widget can be used in scenarios where we need to make all fields in a form read only based on the same Subset or Visibility Dependencies. The subset and/or the dependencies need to be applied only on the custom widget, not on each field individually and when the widget is visible on the page (It is not actually visible, but it will be "active") the fields will become disabled and when the widget is hidden, the fields will remain enabled.
The widget works on page load only.