private void TestType()
        {
            int hr;
            TimelineMajorType t;

            hr = m_pVideoGroupObj.GetTimelineType(out t);
            DESError.ThrowExceptionForHR(hr);

            Debug.Assert(t == TimelineMajorType.Group, "TimelineType");

            hr = m_pVideoGroupObj.SetTimelineType(TimelineMajorType.Effect);
            Debug.Assert(hr == E_INVALIDARG, "Not supported");
        }