/// <summary>
        /// Permite agregar un item a la tabla del stock
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnAgregar_Click(object sender, EventArgs e)
        {
            try
            {
                FrmABM frm = new FrmABM();
                if (frm.ShowDialog() == DialogResult.OK)
                {
                    DataRow fila = this.dt.NewRow();

                    fila["Marca"]  = frm.Elec.Marca;
                    fila["Modelo"] = frm.Elec.Modelo;
                    fila["Precio"] = frm.Elec.Precio;
                    fila["Tipo"]   = frm.Elec.GetType().Name;

                    this.dt.Rows.Add(fila);
                }
            }
            catch (NullReferenceException ex)
            {
                MessageBox.Show("Se intentaron agregar valores nulos");
            }
            catch (ModeloException ex)
            {
                MessageBox.Show(ex.Message);
            }
        }
        /// <summary>
        /// Permite modificar los datos del item seleccionado
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnModificar_Click(object sender, EventArgs e)
        {
            try
            {
                int indice = this.grillaInventario.CurrentRow.Index;

                FrmABM frm = new FrmABM(this.dt.Rows[indice]["Marca"].ToString(),
                                        this.dt.Rows[indice]["tipo"].ToString(),
                                        this.dt.Rows[indice]["Modelo"].ToString(),
                                        this.dt.Rows[indice]["Precio"].ToString());

                if (frm.ShowDialog() == DialogResult.OK)
                {
                    this.dt.Rows[indice]["Marca"]  = frm.Elec.Marca;
                    this.dt.Rows[indice]["Modelo"] = frm.Elec.Modelo;
                    this.dt.Rows[indice]["Precio"] = frm.Elec.Precio;
                    this.dt.Rows[indice]["Tipo"]   = frm.Elec.GetType().Name;
                }
            }
            catch (ModeloException ex)
            {
                MessageBox.Show(ex.Message);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }