title: Drawing widgets (such as buttons) over QGraphicsView
body: <p>How do I draw interactive widgets such as QButtons and Line Edits over a QGraphicsView?
  For ex, I have selected a region over an image in an image editing app which displays an image with QGraphicsView, and I want to annotate this region with a name. </p>
  
  <p>So I want to have a Line edit and two buttons (Cross and Tick) below this rectangular selection.
  How do I draw these?</p>
  
  <p>Sample code would be cool!</p>