Exposing events from .NET to COM

I recently ran into problems when exposing events from .NET to COM.

I worked well with this example (conceptually taken from http://blogs.msdn.com/andreww/archive/2008/10/13/exposing-events-from-managed-add-in-objects.aspx ):

// Delegate type for our custom event.

[ComVisible(false)]
public delegate void SomeEventHandler(object sender, EventArgs e);

// Outgoing (source/event) interface.
[ComVisible(true)]
[InterfaceType(ComInterfaceType.InterfaceIsIDispatch)]
public interface IAddInEvents
{
    [DispId(1)]
    void SomeEvent(object sender, EventArgs e);
}

[ComVisible(true)]
[ClassInterface(ClassInterfaceType.None)]
[ComSourceInterfaces(typeof(IAddInEvents))]
public class AddInUtilities :
{       
    // Event field. This is what a COM client will hook up
    // their sink to.
    public event SomeEventHandler SomeEvent;

    inernal void FireEvent(object sender, EventArgs e)
    {
        if (SomeEvent != null)
        {
            SomeEvent(sender, e);
        }
    }
}

      

        
        
        
      

    

This works great because the IAddInEvents interface is defined as IDispatch . However, I need to post the event source interface, which is IUnknown . I have no control over the event interface as it comes from a third party library (which will also be a consumer of the published events). Whenever I try to connect to events, the VB environment (where I am trying to sink events) crashes, as does the VBA environment that the third party product (ESRI ArcMap) uses.

I was able to (partially) implement the IConnectionPointContainer interface (which COM uses in the background to handle events) manually, then I can flood the event and go to my IConnectionPointContainer implementation. However, this seems like overkill to me, and I think there should be hidden support in .NET. Secondly, with this approach, I immediately lose the support of delegates.

Does anyone have any experience? Thanks in advance.