public RadForm1()
        {
            InitializeComponent();

            DataTable dt = new DataTable();
            dt.Columns.Add("Id", typeof(int));
            dt.Columns.Add("Column1", typeof(decimal));
            dt.Columns.Add("Column2", typeof(string));
            dt.Columns.Add("Column3", typeof(string));
            for (int i = 0; i < 10; i++)
            {
                //No delay
                //dt.Rows.Add(i, 100, "LongstringAAAAAA" + i, "VeryVeryLongstringAAAAAAAABBBBBBBBVeryVeryLongstringAAAAAAAABBBBBBBBE" + i);

                //Long delay
                dt.Rows.Add(i, 10000, "LongstringAAAAAA" + i, "VeryVeryLongstringAAAAAAAABBBBBBBBVeryVeryLongstringAAAAAAAABBBBBBBBE" + i);
            }

            this.radFilterView1.DataSource = dt;
        }

        private void radFilterView1_CategoryCreating(object sender, Telerik.WinControls.UI.FilterView.FilterViewCategoryCreatingEventArgs e)
        {
            FilterViewNumericCategoryElement numericCategory = e.Category as FilterViewNumericCategoryElement;
            if (numericCategory!=null)
            {
                numericCategory.DisplayMode = FilterViewNumericCategoryMode.SpinEditors;
            }
        }