For best results, do not derive a class from the IBorder interface. Instead derive classes from an existing border class, such as the BevelBorder class.

Classes derived from this interface might not behave as expected.

Reference

IBorder Members
FarPoint.Win Namespace
BevelBorder Class
ComplexBorder Class
CompoundBorder Class
DoubleLineBorder Class
EmptyBorder Class
LineBorder Class
RoundedLineBorder Class
Customizing Cell Borders