private void IniciarCamposArticulos()
        {
            LimpiarCamposArticulos();

            txtArtPreUnitario.Attributes.Add("onFocus", "JavaScript:this.select();");
            txtArtDescuento.Attributes.Add("onFocus", "JavaScript:this.select();");
            txtArtCant.Attributes.Add("onFocus", "JavaScript:this.select();");

            clsProveedores lstProveedor = new clsProveedores();
            ddlLaboratorios.DataSource = lstProveedor.GetAll();
            ddlLaboratorios.DataBind();
            ddlLaboratorios.Items.Insert(0, new ListItem("Todos", "-1"));

            clsArticulos oArticulos = new clsArticulos();
            lsbArticulos.DataSource = oArticulos.GetArticulosStock();
            lsbArticulos.DataBind();

            if (lsbArticulos.Items.Count == 0)
            {
                lsbArticulos.Items.Add(new ListItem("No existen Articulos en Stock", "0"));
            }
        }
        protected void ddlLaboratorios_SelectedIndexChanged(object sender, EventArgs e)
        {
            clsArticulos colArticulos = new clsArticulos();
            int PrvCod = Int32.Parse(ddlLaboratorios.SelectedValue);

            if (PrvCod == -1)
                lsbArticulos.DataSource = colArticulos.GetArticulosStock();
            else
                lsbArticulos.DataSource = colArticulos.GetArticulosStockByPrvCod(PrvCod);
            lsbArticulos.DataBind();
            if (lsbArticulos.Items.Count == 0)
            {
                lsbArticulos.Items.Add(new ListItem("Sin Articulos en Stock", "0"));
            }
            colArticulos = null;

            if (lsbArticulos.SelectedIndex >= 0)
                lsbArticulos_SelectedIndexChanged(sender, e);

            ModalPopupAgregar.Show();
        }