title: Transparent QGLWidget on top of QGraphicsView
body: <p>I'm using <code>QGraphicsView</code> to show a 2D image and also have a separate <code>QGLWidget</code> window to display some 3D object. I'm dynamically changing the image displayed in `QGraphicsView' based on the rotation of the 3D object.</p>
  <p>I would like to render a semi-transparent 3D object on top of the 2D image, something like Maya 2009 used to do (notice the cube in the upper right corner of the viewport): <a href="https://i.stack.imgur.com/wdhJA.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/wdhJA.png" alt="Maya 2009 screenshot" /></a><br />
  <sub>(source: <a href="http://www.boulevard-creation.com/images/2008/11/maya2009png.png" rel="nofollow noreferrer">boulevard-creation.com</a>)</sub></p>
  <p>Is it possible to do this with my current widgets? If not, how could it be done?</p>
  <p>One option I can think of would be to render everything in <code>QGLWidget</code> and display the 2D image as a texture on a background plane, but that seems slightly painful.</p>