title: callback/event management with COM/Ole/ActiveX
body: <p>I am writing a native COM/Ole/ActiveX wrapper for a scripting language.
  I need some advices to implement events/callback (like onreadystatechange from Microsoft.XMLHTTP object)</p>
  
  <p>I noticed that some COM objects can call my custom object through an IDispatch interface. Is it the only way to manage events ?</p>