title: QGraphicsView and QGraphicsScene coordinate systems
body: <p>in Qt 4.8 i have create a QGraphicsView and a DynamicRadarScene(derived from QGraphicsScene):</p>
  
  <pre><code>QGraphicsView* view = new QGraphicsView;
  view-&gt;setMinimumSize(800, 600);
  DynamicRadarScene* _scene = new DynamicRadarScene(mode, channel_types, this);
  view-&gt;setScene(_scene);
  </code></pre>
  
  <p>What is the coordinate system of QGraphicsScene? (0,0) is from upper left corner?
  How can i draw an item in the upper right corner of the scene (i have set it 800x600: view->setMinimumSize(800, 600);)?
  If i resize the widget and so i resize the QGraphicsView, how can move the item i have drawn before to remain in the upper left corner?</p>