public static FrmListarPagos GetInstancia()
 {
     if (instancia == null)
     {
         instancia = new FrmListarPagos();
     }
     return(instancia);
 }
        private void btnPagar_Click(object sender, EventArgs e)
        {
            FrmListarPagos frmHijo = new FrmListarPagos();

            AddOwnedForm(frmHijo);
            frmHijo.FormBorderStyle = FormBorderStyle.None;
            frmHijo.TopLevel        = false;
            frmHijo.Dock            = DockStyle.Fill;
            this.Controls.Add(frmHijo);
            this.Tag = frmHijo;
            frmHijo.BringToFront();

            frmHijo.Show();
        }
 private void FrmListarPagos_FormClosing(object sender, FormClosingEventArgs e)
 {
     instancia = null;
 }