The readonly event may be called from web pages developed in Web Designer and processed by a USoft page engine service.
This event applies only to read-only custom UI controls. They are controls with the Type property set to 'custom'.
How to use
Find or create an Event Listener object with Event Type = readonly. Event Listeners are in the Web Designer Controls catalog:
Insert the event listener into the object for the read-only custom UI control. Insert a callClientScript action into the event listener. Use this action's Script property to code the behaviour that you want to see when the event occurs.