QGraphicsView::fitInView() does not work after expanding the view

[lain]

Hi,
I made a main window which has four frames (QFrame) in the grid layout. The first frame has a QGraphicsView to show an image set to QGraphicsPixmapItem.
I tried to implement functionality to "maximize" the first frame by hiding other three frames:

frame2->hide();
frame3->hide();
frame4->hide();
view->fitInView(item, Qt::KeepAspectRatio);

frame2->hide();
frame3->hide();
frame4->hide();
view->fitInView(item, Qt::KeepAspectRatio);

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With the code above the first frame (and the view) is expanded but the size of the image remains unchanged.

Could someone please give me a few pointers?