The following example uses WinMessageBox2 to create a message box containing a customized icon.

#define  INCL_WINDIALOGS                 /* Window Dialog Mgr functions*/
#define  INCL_WINPOINTERS                /* Window Pointer functions   */
#define  NUM_BUT 4
#include <os2.h>

ULONG   ulResult;                        /* Indicates which button to  */
                                         /* push on the message box    */
ULONG   i;                               /* A loop index               */
MB2INFO *pmbInfo;                        /* Pointer to the message box */
                                         /* structure                  */

PSZ      pszBoxTitle     = "A title with up to 40 characters in it  ";

MB2D mb2dBut[NUM_BUT] =
{
  /* Static copy of button definitions */
  { "AAAA",              ID_BUTTON1, BS_PUSHBUTTON},  /* Or use 0 */
  { "BBBBBBBBBBBBBBBBB", ID_BUTTON2, BS_DEFAULT},
  { "CCCCCCCC",          ID_BUTTON3, 0},
  { "D",                 ID_BUTTON4, 0}
};

/* Size of the message box structure needed.         */
/* Need space for MB2INFO plus 3 additional buttons  */
/* (one button is defined in the MB2INFO structure). */
ULONG   ulInfoSize = (sizeof(MB2INFO) + (sizeof(MB2D) * (NUM_BUT-1)));

/* Allocate space for the MB2INFO structure */
pmbInfo = malloc (ulInfoSize);

pmbInfo->cb         = ulInfoSize;        /* Size of block              */
pmbInfo->hIcon      = WinLoadPointer(HWND_DESKTOP, 0, ID_ICON1);
pmbInfo->cButtons   = NUM_BUT;           /* Number of buttons for box  */
pmbInfo->flStyle    = MB_CUSTOMICON |
                      MB_MOVEABLE;
pmbInfo->hwndNotify = NULLHANDLE;

/* Copy information for each button to the MB2INFO structure */
for (i = 0; i < NUM_BUT; i++)
{
  memcpy( pmbInfo->mb2d+i , mb2dBut+i , sizeof(MB2D));
};

ulResult = WinMessageBox2(HWND_DESKTOP,  /* Parent window              */
                          HWND_DESKTOP,  /* Owner window               */
                          (PSZ)"Line 1 of your message.\nLine 2 of message.",
                          pszBoxTitle,   /* Message box title          */
                          1234L,         /* Identifier for message box */
                          pmbInfo);      /* Button definitions for     */
                                         /* message box                */