I tried to use the horizontal and vertical border lines when creating border lines but it was not successful when selecting a rage of cells. Applying lines as vertical and horizontal didn't seem to have any affect to either as one might expect on inside borders when selecting a range. The work around it seems is to select each cell and apply a outline to them all singularly. That causes a performance drop if there are a lot of cells. Does anyone else know how to apply borders to inside cells within a range or does everyone handle it when the write a value to a cell regardless if it has any value or not?
This feature request has been implemented and is available in the latest versions of GemBox.Spreadsheet.