c# 폼의 중복실행 방지

        private void ConfigToolStripMenuItem_Click(object sender, EventArgs e)
        {
            foreach (Form frm in Application.OpenForms)
            {
                if (frm.Name == "frmConfig")

                    frm.Activate();
                    return;
            }

            frmConfig configForm = new frmConfig();
            configForm.Show();
        }