This function creates a message-box window that can be used to display error messages and ask questions.

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

HWND        hwndParent;  /*  Parent-window handle of the message-box window to be created. */
HWND        hwndOwner;   /*  Requested owner-window handle of the message-box window to be created. */
PSZ         pszText;     /*  Message-box window message. */
PSZ         pszTitle;    /*  Message-box window title. */
ULONG       ulWindow;    /*  Message-box window identity. */
PMB2INFO    pmb2info;    /*  Input structure for mesage-box window. */
ULONG       ulButtonId;  /*  Id of the button that was clicked, or MBID_ERROR. */

ulButtonId = WinMessageBox2(hwndParent, hwndOwner,
               pszText, pszTitle, ulWindow,
               pmb2info);