To implement a configuration management user interface for an Extension add this interface to a Windows Form that will be your custom configuration dialog. Loupe will create & dispose the interface as required. An Extension (e.g. a particular IExtensionDefinition implementation) can only have a single configuration editor associated with it, and it must be declared in the LoupeExtensionAttribute on the IExtensionController implementation. This is necessary because the configuration editor is used when initially configuring and enabling the Extension before it is initialized the first time.

Reference

IConfigurationEditor Members
Loupe.Extensibility.Client Namespace