This function creates, displays, and operates a message box window.

#define INCL_WINDIALOGS /* Or use INCL_WIN, INCL_PM, Also in COMMON section */
#include <os2.h>

HWND     hwndParent;  /*  Parent-window handle of the created message-box window. */
HWND     hwndOwner;   /*  Requested owner-window handle of the created message-box window. */
PSZ      pszText;     /*  Message-box window message. */
PSZ      pszCaption;  /*  Message-box window title. */
ULONG    idWindow;    /*  Message-box window identity. */
ULONG    flStyle;     /*  Message-box window style. */
ULONG    usResponse;  /*  User-response value. */

usResponse = WinMessageBox(hwndParent, hwndOwner,
               pszText, pszCaption, idWindow,
               flStyle);