The WinReplaceObjectClass function replaces a registered class with another registered class. If fReplace is FALSE, pOldClassName will revert back to its original definition.

#define INCL_WINWORKPLACE
#include <os2.h>

PSZ     pOldClassName;  /*  Pointer to class name. */
PSZ     pNewClassName;  /*  Pointer to new class name. */
BOOL    fReplace;       /*  Function replacement flag. */
BOOL    rc;             /*  Success indicator. */

rc = WinReplaceObjectClass(pOldClassName,
       pNewClassName, fReplace);