BCGSuite for MFC
BCGCBPRODLLEXPORT UINT BCGM_ON_CHART_MOUSE_TRACK

The framework sends the BCGM_ON_CHART_MOUSE_TRACK message when you enable mouse tracking with CBCGPChartVisualObject::EnableMouseTrackingMode.

Parameters
wParamID of chart visual object.
lParama pointer to a BCGPChartHitInfo structure.
Returns
TRUE - disable further mouse move processing. In this case scrolling / selection will not occur (if enabled).

You should process this message to implement interactive charts.