how to hide menubar in qt(symbian)

Question 1: I create menubar with below code

Qt::WindowFlags flags = win开发者_JS百科dowFlags();
flags |= Qt::WindowSoftkeysVisibleHint;
setWindowFlags(flags);
showFullScreen();

I want hide the menubar, what shall do now?

Question 2: When i switch my app to background(long press home), it will enter the runing app list, it's ok, but there's a menubar with a exit button at the bottom, how can i remove it?

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Normally when you enter full screen on Symbian, soft-keys are disabled (not shown on screen). With your code, soft-keys are enabled in full screen also.

If you wont soft-keys in full screen, then leave window flags untouched.

How do you switch your app into background?