QT bug? Or win 7?

[been_1990]

I have a widget with these flags and attributes:

setWindowFlags(Qt::SubWindow | Qt::FramelessWindowHint );
setTransformationAnchor(QGraphicsView::AnchorViewCenter);
 
this->setAttribute(Qt::WA_TranslucentBackground);
this->setAttribute(Qt::WA_TransparentForMouseEvents);

setWindowFlags(Qt::SubWindow | Qt::FramelessWindowHint );
setTransformationAnchor(QGraphicsView::AnchorViewCenter);

this->setAttribute(Qt::WA_TranslucentBackground);
this->setAttribute(Qt::WA_TransparentForMouseEvents);

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To make the window always on top:

setWindowFlags(Qt::FramelessWindowHint | Qt::SubWindow | Qt::WindowStaysOnTopHint);

setWindowFlags(Qt::FramelessWindowHint | Qt::SubWindow | Qt::WindowStaysOnTopHint);

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So when the app runs, the window is on top of every other window, but as soon as I click any other window it goes behind the windowI clicked.
Why this behaviour?