次のサンプルコードは、SetInsideBorderメソッドを使用します。
fpSpread1.Sheets[0].SetInsideBorder(new FarPoint.Win.Spread.Model.CellRange(0, 0, 2, 2), new FarPoint.Win.BevelBorder(FarPoint.Win.BevelBorderType.Raised));
FpSpread1.Sheets(0).SetInsideBorder(New FarPoint.Win.Spread.Model.CellRange(0, 0, 2, 2), New FarPoint.Win.BevelBorder(FarPoint.Win.BevelBorderType.Raised))