private void button3_Click(object sender, EventArgs e)
        {
            AgregarCliente agregarCliente = new AgregarCliente();

            agregarCliente.Show();
            this.Hide();
        }
        private void button2_Click(object sender, EventArgs e)
        {
            AgregarCliente agregarCliente = new AgregarCliente();

            agregarCliente.ShowDialog();
            DisplayCliente();
        }
        private void btnEditar_Click(object sender, EventArgs e)
        {
            int?id = GetId();

            if (id != null)
            {
                AgregarCliente agregarCliente = new AgregarCliente(id);
                agregarCliente.ShowDialog();
                DisplayCliente();
            }
        }