| UINT BCGM_ON_CHART_MOUSE_TRACK | 
The framework sends the BCGM_ON_CHART_MOUSE_TRACK message when you enable mouse tracking with CBCGPChartVisualObject::EnableMouseTrackingMode.
| wParam | ID of chart visual object. | 
| lParam | a pointer to a BCGPChartHitInfo structure. | 
You should process this message to implement interactive charts.