Class CRtnInfo Overview

        CRtnInfo is a very base class for all the classes of this module, except COPropSet. It remembers a returned value (m_hr) from a call of an interface method, an error message (m_strError) and a pointer to a function (m_pGetErrorInfo) used for retrieving the error message.

        If you don't want to retrieve error message, you can simply set the function pointer to NULL. If you don't want the default function provided with this module, you can set the function pointer to yours.