private void BtnCalcular_Click(object sender, EventArgs e)
        {
            if (TxtLargo.Text.Trim().Length == 0)
            {
                POO.MsgWarning("Ingresar el Largo del Tanque.");
                TxtLargo.Focus();
            }
            if (TxtAlto.Text.Trim().Length == 0)
            {
                POO.MsgWarning("Inngresar el Alto del Tanque.");
                TxtAlto.Focus();
            }
            if (TxtAncho.Text.Trim().Length == 0)
            {
                POO.MsgWarning("Ingresar el Ancho del Tanque.");
                TxtAncho.Focus();
            }

            double lar, alt, anch;

            lar  = Convert.ToDouble(TxtLargo.Text.Trim());
            alt  = Convert.ToDouble(TxtAlto.Text.Trim());
            anch = Convert.ToDouble(TxtAncho.Text.Trim());

            TxtResultado.Text = POO.Tanque(lar, alt, anch).ToString();
        }
 private void BtnLimpiar_Click(object sender, EventArgs e)
 {
     foreach (TextBox txt in this.Controls.OfType <TextBox>())
     {
         txt.Clear();
         TxtLargo.Focus();
     }
 }