This example obtains a pointer to the window procedure of the window class WC_COMBOBOX.

#define INCL_WINWINDOWMGR
#define INCL_WINENTRYFIELDS

#include <OS2.H>

HAB       hab;
CLASSINFO classinfo;
PFNWP     pWindowProc;

WinQueryClassInfo(hab,
                  WC_COMBOBOX,
                  &classinfo);

pWindowProc = classinfo.pfnWindowProc;