private static System.Type GetValueTypeFromTypeDesc(System.Windows.Forms.NativeMethods.tagTYPEDESC typeDesc, UnsafeNativeMethods.ITypeInfo typeInfo, object[] typeData, StructCache structCache)
        {
            IntPtr unionMember;
            int hr = 0;
            switch (((System.Windows.Forms.NativeMethods.tagVT) typeDesc.vt))
            {
                case System.Windows.Forms.NativeMethods.tagVT.VT_DISPATCH:
                case System.Windows.Forms.NativeMethods.tagVT.VT_UNKNOWN:
                    typeData[0] = GetGuidForTypeInfo(typeInfo, structCache, null);
                    return VTToType((System.Windows.Forms.NativeMethods.tagVT) typeDesc.vt);

                case System.Windows.Forms.NativeMethods.tagVT.VT_PTR:
                {
                    System.Windows.Forms.NativeMethods.tagTYPEDESC data = (System.Windows.Forms.NativeMethods.tagTYPEDESC) structCache.GetStruct(typeof(System.Windows.Forms.NativeMethods.tagTYPEDESC));
                    try
                    {
                        try
                        {
                            UnsafeNativeMethods.PtrToStructure(typeDesc.unionMember, data);
                        }
                        catch
                        {
                            data = new System.Windows.Forms.NativeMethods.tagTYPEDESC {
                                unionMember = (IntPtr) Marshal.ReadInt32(typeDesc.unionMember),
                                vt = Marshal.ReadInt16(typeDesc.unionMember, 4)
                            };
                        }
                        if (data.vt == 12)
                        {
                            return VTToType((System.Windows.Forms.NativeMethods.tagVT) data.vt);
                        }
                        unionMember = data.unionMember;
                    }
                    finally
                    {
                        structCache.ReleaseStruct(data);
                    }
                    break;
                }
                case System.Windows.Forms.NativeMethods.tagVT.VT_USERDEFINED:
                    unionMember = typeDesc.unionMember;
                    break;

                default:
                    return VTToType((System.Windows.Forms.NativeMethods.tagVT) typeDesc.vt);
            }
            UnsafeNativeMethods.ITypeInfo pTypeInfo = null;
            hr = typeInfo.GetRefTypeInfo(unionMember, ref pTypeInfo);
            if (!System.Windows.Forms.NativeMethods.Succeeded(hr))
            {
                throw new ExternalException(System.Windows.Forms.SR.GetString("TYPEINFOPROCESSORGetRefTypeInfoFailed", new object[] { hr }), hr);
            }
            try
            {
                if (pTypeInfo != null)
                {
                    IntPtr zero = IntPtr.Zero;
                    hr = pTypeInfo.GetTypeAttr(ref zero);
                    if (!System.Windows.Forms.NativeMethods.Succeeded(hr))
                    {
                        throw new ExternalException(System.Windows.Forms.SR.GetString("TYPEINFOPROCESSORGetTypeAttrFailed", new object[] { hr }), hr);
                    }
                    System.Windows.Forms.NativeMethods.tagTYPEATTR gtypeattr = (System.Windows.Forms.NativeMethods.tagTYPEATTR) structCache.GetStruct(typeof(System.Windows.Forms.NativeMethods.tagTYPEATTR));
                    UnsafeNativeMethods.PtrToStructure(zero, gtypeattr);
                    try
                    {
                        Guid g = gtypeattr.guid;
                        if (!Guid.Empty.Equals(g))
                        {
                            typeData[0] = g;
                        }
                        switch (gtypeattr.typekind)
                        {
                            case 0:
                                return ProcessTypeInfoEnum(pTypeInfo, structCache);

                            case 3:
                            case 5:
                                return VTToType(System.Windows.Forms.NativeMethods.tagVT.VT_UNKNOWN);

                            case 4:
                                return VTToType(System.Windows.Forms.NativeMethods.tagVT.VT_DISPATCH);

                            case 6:
                                return GetValueTypeFromTypeDesc(gtypeattr.Get_tdescAlias(), pTypeInfo, typeData, structCache);
                        }
                        return null;
                    }
                    finally
                    {
                        pTypeInfo.ReleaseTypeAttr(zero);
                        structCache.ReleaseStruct(gtypeattr);
                    }
                }
            }
            finally
            {
                pTypeInfo = null;
            }
            return null;
        }