Progress!
1. attach a mouselistener to the chart
2. use chart.getNearestPointManhattan(arg0).getListener().getLabel() to find the label (for example) for the POINT (not line, just point) closest to your mouse.
From there, you can manipulate the trace, I suppose. I am hoping to find a more elegant solution, but this is a start.
2009-06-30 13:48:53 UTC in JChart2D
