How do you apply alternating styles to groups of records?

v9.0p_2014-07-12/PowerEdition

I am trying to override the styling used for grouped records. I have disabled the alternate record styles. My ListGrid will always be grouped, and I want each group of records to alternate background color like in the attached image.

I've tried overriding getBaseStyle() and using some math to perform the styling - which works until I start collapsing groups. Then the row numbering can no longer be used with my formula, as it depends on one group always using 9 rows in the grid.

Is there a way in your API to set a style for a group at a time? Or do you have any other ways to approach this?

Attached Images

alternating group styles.jpg (140.2 KB)