This example uses WinEnableWindowUpdate to set a window's WS_VISIBLE style to visible and cause the window to be updated by a WM_PAINT message.

#define INCL_WINWINDOWMGR       /* Window Manager Functions     */
#include <os2.h>

HWND    hwnd;           /* parent window                        */
BOOL  fSuccess;         /* success indicator                    */

case WM_CREATE:
     /* if window has WS_VISIBLE off, set state to visible */
     if (!WinIsWindowVisible(hwnd))
        {
        /* set state to visible and cause WM_PAINT message */
        fSuccess = WinEnableWindowUpdate(hwnd, EWUF_ENABLE);
        }