private void 右下がり罫線_Click(object sender, RibbonControlEventArgs e)
        {
            //選択範囲の取得
            Range selection = (Range)Globals.ThisAddIn.Application.Selection;
            //選択範囲の数
            int count = selection.Areas.Count;
            //複数選択範囲を配列に入れる
            Range[] allRange = new Range[count];
            //それぞれの選択範囲について繰り返す
            foreach (Range r in selection.Areas)
            {
                //右下がり罫線を引く
                r.Borders.get_Item(XlBordersIndex.xlDiagonalDown).LineStyle = XlLineStyle.xlContinuous;
            }
        }