BCGSuite for MFC
BCGCBPRODLLEXPORT UINT BCGM_ONDRAWCUSTOMINFOTIP

The message is sent to the dialog before the framework draws the control information tip.

Parameters
wParamA handle of the dialog's device content (HDC) where the info tip is drawed.
lParamA pointer to the currently rendered information tip (CBCGPControlInfoTip).
Returns
non-zero if custom tooltip drawing was performed; FALSE - use a default drawing.
See also
CBCGPDialog::SetControlInfoTip, CBCGPFormView::SetControlInfoTip, CBCGPPropertyPage::SetControlInfoTip, CBCGPDialogBar::SetControlInfoTip