Overlapping windows on Mac OS X

I am trying to implement a starup banner that should be shown above the main application window. It works fine on Windows, but on Mac OS X I can't get two windows shown at the same time (unless I show the banner after a some large time interval). Is there a way to ensure the window is visible on the screen before showing another one?

This is how I tried it:

Code:

---

#include <QApplication> 
 
#include "mainwindow.h"
#include "banner.h"
 
int main(int argc, char * argv[])
{
    QApplication app(argc, argv);
 
    MainWindow mainWindow;
    mainWindow.show();
    //mainWindow.raise();
 
    Banner banner;
    //QTimer::singleShot(0, &banner, SLOT(show()));    
    //QTimer::singleShot(0, &banner, SLOT(raise()));
    banner.show();
 
    return app.exec();
}

---

I tried to use show, raise, delayed show/raise with zero-time interval, but nothing helps: still I see only the banner window when the application is launched, the main window becomes visible only when I click the application icon on the task bar.

Have you seen QSplashScreen?

Yes, I did, but that is different to what I really need. However, with QSplashScreen I also have only one window displayed: if I first show the splash screen it gets hidden by the main window when it shown, otherwise, I see only the splash screen while the main window is hidden - the behavior is wrong in both cases.

I've found the code that seems to be related to the issue I am pointing out:

Code:

---

#ifdef Q_WS_X11
 void qt_x11_wait_for_window_manager(QWidget *widget);
 #endif
 
 int main(int argc, char *argv[])
 {
     QApplication app(argc, argv);
     ...
     window.show();
 #ifdef Q_WS_X11
     qt_x11_wait_for_window_manager(&window);
 #endif
     ...
     return app.exec();
 }

---

According to the documentation, qt_x11_wait_for_window_manager blocks until the X11 window manager has shown the widget after a call to QWidget::show(). That is exactly what I need to fix the wrong behavior. Is it possible to do something similar on Mac OS X?