BCGControlBar Pro for MFC
virtual void CBCGPGridCtrl::GetItemCustomTooltip ( const CBCGPGridItemID id,
CString &  strText,
CString &  strDescription 
) const

Called by the framework to obtain the cell custom tooltip.

idThe Grid cell identifier.
strTextThe tooltip text. Leave it empty if you don't wish to display the toolip.
strDescriptionThe tooltip description.

You've to call EnableCustomToolTips() method to enable or disable the custom tooltips.