Replied 17 December 2020, 11:04 pm EST
Since, Spread.NET v7 is very old version, it's support is no more provided. Therefore, we will be answering your concern according to Spread.NET v14.
To show complex border, you should use ComplexBorder with ComplexBorderSide of type DoubleLine while setting the outline border. Please refer to the sample attached.SpreadDoubleBorder.zip
Alternatively, you can also use any of the following way depending on your requirement:Column
FpSpread1.ActiveSheet.Columns(0).Border = New FarPoint.Win.DoubleLineBorder(Color.Red)Single cell/cell-range
Dim doubleLine As DoubleLineBorder = New DoubleLineBorder(Color.Red)
FpSpread1.Sheets(0).Cells(10, 10).Border = doubleLine
FpSpread1.Sheets(0).Cells(1, 2, 8, 5).Border = doubleLine