BCGSuite for MFC
BCGCBPRODLLEXPORT const UINT BCGM_GANTT_CONTROL_CREATE_GRID

This message is sent to owner of Gantt control when it's about to create a Grid pane.

Parameters
wParamThis parameter is not used.
lParamThis parameter is not used.
Returns
A pointer to a newly created Grid control.

You should process this message in the parent window if you wish to create a custom CBCGPGanttGrid - derived Chart pane.