A client recently asked us to help them construct a new custom property in their existing EPiServer 4-based site. I've successfully constructed a basic custom property, inheriting from the LongString property, but can't figure out how to save the value in the editing interface based to the repository. The editing interface consists of a custom composite .NET web control that outputs XML. I'd like to persist the value from this control as the value for the property.
All of the examples I've seen are for either v5 or v6, but not for v4. It's not clear what needs to be overriden for a v4 property. Any help would be greatly appreciated.