private void RadForm1_Load(object sender, EventArgs e)
        { 
            this.productsTableAdapter.Fill(this.nwindDataSet.Products);
            this.radGridView1.BestFitColumns();

            this.radGridView1.EnableCustomSorting = true;
            this.radGridView1.CustomSorting += radGridView1_CustomSorting;
        }

        private void radGridView1_CustomSorting(object sender, GridViewCustomSortingEventArgs e)
        {
            if (this.radGridView1.SortDescriptors.Contains("ProductID"))
            {
                //use custom sorting logic
                e.Handled = true;
                e.SortResult = e.Row1.Cells["ProductID"].Value.ToString().CompareTo(e.Row2.Cells["ProductID"].Value.ToString());
            }
            else
            {
                //leave the basic sorting logic
                e.Handled = false;
            }
        }