[fpspread][c#] cell border style

using using FarPoint.Win;
using System.Drawing.Drawing2D;

int _sheetIndex = 0;
var targetCell = sprList.Sheets[_sheetIndex].Cells[row, col];

ComplexBorderSide borderStyle = new ComplexBorderSide(Color.Black, 1, DashStyle.Solid);        //Thin line

targetCell .Border = new ComplexBorder(null, null, borderStyle, borderStyle);