private void mn_conf_canal_Click(object sender, EventArgs e) { Form FRM_MANT_CANALES = Application.OpenForms.OfType <Form>().Where(pre => pre.Name == "FRM_MANT_CANALES").SingleOrDefault(); if (FRM_MANT_CANALES == null) { FRM_MANT_CANALES frm = new FRM_MANT_CANALES(); frm.MdiParent = this; frm.Show(); } }