Public Interface IPlugInMain
  Public Function MainPlugin_Receivemessage( ByVal Sender IPlugIn, ByVal _
    Message As CirculiSDK.PC.Circuli.IPlugIn.Messages ) as Integer
End Interface

Public Class Form1
  Inherits System.Windows.Forms.Form
  Implements IPlugInMain
...
 
  Public Function MainPlugin_Receivemessage( ByVal Sender IPlugIn, ByVal _
    Message As CirculiSDK.PC.Circuli.IPlugIn.Messages ) as Integer Implements _
    IPlugInMain.MainPlugin_Receivemessage
  ....
  End Function

public class Form1 : System.Windows.Forms.Form, IPlugInMain

Public Class Form1
  Inherits System.Windows.Forms.Form
  Implements IPlugInMain