private void PostPageChanges()
        {
            MaterialsNavigator materialsNavigator = new MaterialsNavigator(materialsNavigatorTDS);

            // Update
            foreach (GridViewRow row in grdNavigator.Rows)
            {
                int materialId = Int32.Parse(((Label)row.FindControl("lblMaterialId")).Text.Trim());
                bool selected = ((CheckBox)row.FindControl("cbxSelected")).Checked;

                materialsNavigator.Update(materialId, selected);
            }

            materialsNavigator.Data.AcceptChanges();

            // Store datasets
            Session["materialsNavigatorTDS"] = materialsNavigatorTDS;
        }