title: Scaling an already drawn QPolygonF in drawing
body: <p>So, 
  I draw a QPolygonF in an area which I define. The area inherits from QGraphicsView.</p>
  
  <p>What I want to be able to do is let user move around the control points of QPolygonF and alter the polygon even after it has been created. I couldn't really find references to how I could do this. </p>
  
  <p>Since I draw lines to close and denote the polygon, and there can me a lot more things in the drawable area, clearing it and drawing it over and over doesn't seem right. </p>
  
  <p>Does anyone know how I could solve this ? </p>
  
  <p>Thanks !</p>