This topic is included for completeness. For more detail see the source code located in the VC\atlmfc\src\mfc folder of your Visual Studio installation.
virtual CSize OnDrawDescription(
CDC* pDC,
CRect rect,
BOOL bCalcOnly
);
Parameters
[in] pDC
[in] rect
[in] bCalcOnly
Requirements
Header: afxtooltipctrl.h