private sgFrmManage getManage()
 {
     if (sgFrmManage == null || sgFrmManage.IsDisposed)
     {
         sgFrmManage           = new sgFrmManage();
         sgFrmManage.MdiParent = this;
     }
     else
     {
         sgFrmManage.Activate();
     }
     return(sgFrmManage);
 }
        private void bManage_Click(object sender, EventArgs e)
        {
            sgFrmManage sgFrmManage = getManage();

            sgFrmManage.Show();
        }