I have an existing (unchangeable) native application that uses
(currently only native) COM plug-ins.  The application communicates
with its plug-ins via an automation interface (IDispatch only).  The
COM plug-ins return errors by calling AfxThrowOleDispatchException
passing a 16-bit error code and error string.  This results in the
application receiving an HRESULT of DISP_E_EXCEPTION from the Invoke
call, and a filled in EXCEPINFO structure containing the wCode and
bstrDescription specified by the plug-in.

I would like to implement a new plug-in for this application in C#
using a CCW, but I can't figure out how to pass back the wCode value.
I can throw an Exception(String) object containing an error message,
which makes it back to the native application in
EXCEPINFO.bstrDescription (along with EXCEPINFO.scode = 0x80131500 --
not sure what that is), or I can throw a COMException(String, Int32)
object with an error message and an error code, but this returns the
error code value in the EXCEPINFO.scode member (with a wCode value of
zero).  I don't seem to be able to find a way to pass back a wCode
value.

Because I can't change the native application, I really need to find a
way of passing the wCode back to the application.  Can anyone please
help?

Thanks,
Gary