patron singleton c#

singleton.cs

        private static UIMedicos_Convenios frmConvenios;

        public static UIMedicos_Convenios CreateInstante(System.Windows.Forms.Form FormParent)
        {
            if (frmConvenios == null || frmConvenios.IsDisposed)
            {
                frmConvenios = new UIMedicos_Convenios();
            }
            frmConvenios.BringToFront();
            frmConvenios.MdiParent = FormParent;
            frmConvenios.Show();
            return frmConvenios;
        }