In this project I ran on a S60 mobile device, inside a QMainWindow, if I open a second QMainWindow

Window2* w = new Window2(this);
w->showFullScreen();

then close this second QMainWindow,
I'm back to the first QMainWindow with a default menubar -- empty left soft key and an "Exit" soft key on the right. I want the soft keys I setup.
Calling w->show() instead of w->showFullScreen() would achieve this, but then w, the second QMainWindow would have a title pane on the top.

When working with multiple QMainWindows, what do I need to do so they would open full screen, but the original QMainWindow would always have its softkeys shown after closing a child QMainWindow?

Any help is appreciated!! Thanks in advance

Attached is a Qt project that illustrates this problem:
TestSoftkeys.zip