The information in this topic pertains only to applications written in C++.

If your application uses DirectDraw in windowed mode, you can create windows with any window style. However, full-screen exclusive mode applications cannot be created with the WS_EX_TOOLWINDOW style without risk of unpredictable behavior. The WS_EX_TOOLWINDOW style prevents a window from being the top most window, which is required for a DirectDraw full-screen, exclusive mode application.

Full-screen exclusive mode applications should use the WS_EX_TOPMOST extended window style and the WS_VISIBLE window style to display properly. These styles keep the application at the front of the window z-order and prevent GDI from drawing on the primary surface.

The following example shows one way to safely prepare a window to be used in a full-screen, exclusive mode application.

////////////////////////////////////////////////////////
// Register the window class and display the window.
////////////////////////////////////////////////////////
BOOL WINAPI InitApp(INT nWinMode)
{
    WNDCLASSEX wcex;
 
    wcex.cbSize           =    sizeof(WNDCLASSEX);
    wcex.hInstance        =    g_hinst;
    wcex.lpszClassName    =    g_szWinName;
    wcex.lpfnWndProc      =    WndProc;
    wcex.style            =    CS_VREDRAW|CS_HREDRAW|CS_DBLCLKS;
    wcex.hIcon            =    LoadIcon (NULL, IDI_APPLICATION);
    wcex.hIconSm          =    LoadIcon (NULL, IDI_WINLOGO);
    wcex.hCursor          =    LoadCursor (NULL, IDC_ARROW);
    wcex.lpszMenuName     =    MAKEINTRESOURCE(IDR_APPMENU);
    wcex.cbClsExtra       =    0 ;
    wcex.cbWndExtra       =    0 ;
    wcex.hbrBackground    =    GetStockObject (NULL_BRUSH);
 
    RegisterClassEx(&wcex);
 
    g_hwndMain = CreateWindowEx(
                        WS_EX_TOPMOST,
                        g_szWinName,
                        g_szWinCaption,
                        WS_VISIBLE|WS_POPUP,
                        0,0,0,0,
                        NULL,
                        NULL,
                        g_hinst,
                        NULL);
 
    if(!g_hwndMain)
        return(FALSE);
 
    SetFocus(g_hwndMain);
    ShowWindow(g_hwndMain, nWinMode);
    UpdateWindow(g_hwndMain);
 
    return TRUE;
}