if (column == 0 || column == 4)
                {
                    if (xitem.Tag is User && yitem.Tag is User)
                    {
                        User xuser = (User)xitem.Tag;
                        User yuser = (User)yitem.Tag;
                        if (column == 0)
                        {
                            if (xuser.OP != yuser.OP)
                            {
                                if (xuser.OP)
                                    return -1;
                                return 1;
                            }
                        }
                        else if (column == 4)
                        {
                            long xshare = 0;
                            long yshare = 0;
                            long.TryParse(xuser.UserInfo.ExactShare, out xshare);
                            long.TryParse(yuser.UserInfo.ExactShare, out yshare);
                            if (xshare == yshare)
                                return 0;
                            if (xshare > yshare)
                                return -1;
                            else
                                return 1;
                        }
                    }
                }