private void ShowNewForm(object sender, EventArgs e)
        {
            FrmSueldo frm1 = new FrmSueldo();

            frm1.MdiParent = this;
            frm1.Show();
        }
        private void btnSueldo_Click(object sender, EventArgs e)
        {
            FrmSueldo frm1 = new FrmSueldo();

            frm1.ShowDialog();
        }