1) Run org.apache.pivot.demos.tables.FixedColumnTable
2) Select "User 6" row
3) Move your mouse between the "User 5" and "User 7" rows
As you move your mouse above and below the selected row, columns a, b, and c toggle an extra row of pixels painted selected. The extra row of pixels of very subtle, but it's noticeable when you follow the steps above.