c++ - Win32 ::SetForegroundWindow() not working all the time

Question

I'm working on a messenging tool. The messaging window is part of a whole application. I need the window to go to the front when there are some messages coming. I'am using this code :

    if( m_hwnd == NULL || !::IsWindow(m_hwnd) )
        return E_UNEXPECTED;

    if(::IsIconic(m_hwnd))
    {
        ::ShowWindowAsync( m_hwnd, SW_RESTORE );
    }
    ::SetWindowPos(m_hwnd, HWND_TOP, 0, 0, 0, 0, SWP_ASYNCWINDOWPOS | SWP_NOMOVE | SWP_NOSIZE | SWP_SHOWWINDOW);
    ::SetForegroundWindow(m_hwnd);
    if( pvbProcessed != NULL )
        *pvbProcessed = VARIANT_TRUE;

    return S_OK;

I even tried to do a TOPMOST but still in some cases it does not work. I also Tried a ::BringToFront().

Anyone can help or give an explanation on why it doen not work ? Is it a known microsoft limitation.

Answer 1

The system restricts which processes can set the foreground window. A process can set the foreground window only if one of the following conditions is true:

• The process is the foreground process.
• The process was started by the foreground process.
• The process received the last input event.
• There is no foreground process.
• The foreground process is being debugged.
• The foreground is not locked (see LockSetForegroundWindow).
• The foreground lock time-out has expired (see SPI_GETFOREGROUNDLOCKTIMEOUT in SystemParametersInfo).
• No menus are active.

See the SetForegroundWindow() docs for more details.