I'm having a little bit of trouble reverse engineering the structure of a default plugin; i.e., which classes are held as instances of which classes, which classes are communicating, is IGraphics an instance contained within an IGEditorDelegate, how do the graphics editor delegate and the DSP "editor delegate" communicate, etc. My friends who have tried using IPlug generally have the same experience. The doxygen does a good job of showing inheritance, but if there were a class diagram for the default IPlugEffect that showed how all the classes are related to each other, including which ones are communicating, which one is keeping an instance of another class as a member, etc. then IPlug would be a much more approachable library while there are still not very many advanced code examples.

If I manage to figure out the class structure myself, I will attempt to draw a diagram, probably with UMLet.