private void DGUserEdit()
        {
            if(DGUser.SelectedItem!=null)
            {
                DataRow dr = (DGUser.SelectedItem as DataRowView).Row;
                Page.UserEdit UE = new UserEdit(UserGrade, dr["UserName"].ToString());//声明子窗体
                UE.Closed += new EventHandler(UE_Closed);//注册关闭事件
                UE.ShowDialog();                
            }
        }
        //在子窗体的关闭里写要刷新的内容，我这是重写绑定
        private void UE_Closed(object sender,EventArgs e)
        {
            Band();
        }