Satya,

Here's an example of how things are defined in C# for ATL to catch the
event.
Define a delegate & a corresponding event. Also an interface containing
equivalent method. Note the event instance name, must be same as the
interface method for AtlAdvise to succeed.
public event DefaultButtonHandler DefaultButton;

// Delegate Definitions...

[InterfaceType(ComInterfaceType.InterfaceIsIDispatch)]

public interface IHostMessageSink

{

[DispId(1)] void DefaultButton(int nCtrlIndex);

}

//C# side

public delegate void DefaultButtonHandler(int nCtrlIndex);

[

ComVisible(true),

Guid("1A151E44-FE24-4172-8D5D-FD7A30BA85EB"),

ClassInterface(ClassInterfaceType.None),

ComSourceInterfaces(typeof(IHostMessageSink))

]

public class CWindowHost : System.Windows.Forms.UserControl

{

// Event Definitions..

public event DefaultButtonHandler DefaultButton;

}

Try this out.

Thanks,

VT