Sets parameters for the flat border surrounding the graphic bar. This method is ignored if the border of the graphic bar has been set to 3D mode by setting the bAppearance3d parameter of the GRAPHIC_BAR_SETTINGS structure to "True".
In the graphics below you can see the flat border having a width set to two pixels and the color set to green.
For further details about methods of the Graphic Bars Manager refer to the GraphicBarsMan class.
For a tutorial about the use of the Graphic Bars Manager refer to the How to perform custom feedbacks rendering using graphic bars section.