title: QPropertyAnimation for rotating QWidget
body: <p>I'm new to Qt and I'm having some problem with <code>QWidget</code> rotation. </p>
  
  <p><strong>I have a QPixmap inside a QLabel.
  What I want is to animate it with a continuous rotation by 90 degrees.</strong></p>
  
  <p>I know <code>QPropertyAnimation</code> and I know how to use it, but I'm struggling with How to use it for rotating a <code>QWidget</code>. Is there any simple way to use achieve my goal and rotate the entire <code>QLabel</code> or the <code>QPixmap</code> inside it with an animation?
  Thank you.</p>