This function returns window class information.

#define INCL_WINWINDOWMGR /* Or use INCL_WIN, INCL_PM, */
#include <os2.h>

HAB           hab;             /*  Anchor-block handle. */
PSZ           PSZClassName;    /*  Class name. */
PCLASSINFO    PclsiClassInfo;  /*  Class information structure. */
BOOL          rc;              /*  Class-exists indicator. */

rc = WinQueryClassInfo(hab, PSZClassName,
       PclsiClassInfo);