private void btnBuscar_Click(object sender, EventArgs e)
        {
            frmBuscarLector lector = new frmBuscarLector();

            lector.enviar = 3;
            lector.ShowDialog();
        }
        private void btnSeleccionar_Click(object sender, EventArgs e)
        {
            frmBuscarLector lec = new frmBuscarLector();

            lec.indicador = 1;
            lec.ShowDialog();
        }
        private void btnSelecLec_Click(object sender, EventArgs e)
        {
            frmBuscarLector lector = new frmBuscarLector();

            lector.lista.Clear();
            foreach (DataGridViewRow i in frmPrincipal.alquileres.alquileresDataGridView.Rows)
            {
                lector.lista.Add(new entidades.Alquileres {
                    Id_Lector = int.Parse(i.Cells[1].Value.ToString())
                });
            }
            lector.lector.Clear();
            lector.lector1.Clear();

            lector.enviar = 1;
            lector.ShowDialog();
        }