This association is actually performed in the next tutorial - Tutorial 5. Here is the VB.NET equivalent code:

<ItemEditorAttribute(GetType(MyAppEditor))> _
Public Class MyApp
    Inherits Appointment
... 

This code snippet assumes you have already defined the MyAppViewer class.

The code above represents a declaration of a new class (a custom appointment class). This is done because the association of a custom item viewer with an appointment is performed on a class level using attributes and cannot be accomplished at run-time. Therefore, you cannot place it in the form's Load event handler because new classes cannot be declared inside methods. It would be best to place it in a separate file.

I hope this helps.

Meppy