title: How to add custom items to QFileDialog?
body: <p>I am using non-native <code>QFileDialog</code> (for choosing directory path) and I need to add some custom drives. I don't even need to display any content inside of these drives for now, I just need to display these drives on the top level (and preferably with my icon) and output some special string in the result when user selects it.</p>
  
  <p><a href="https://i.stack.imgur.com/QrwFO.png" rel="noreferrer"><img src="https://i.stack.imgur.com/QrwFO.png" alt="enter image description here"></a></p>
  
  <p>What is the easiest way to implement this?</p>
  
  <p>I have read in the <a href="http://doc.qt.io/qt-5/qfiledialog.html#setProxyModel" rel="noreferrer">documentation</a> that proxy model can be used for that, but I don't understand how to implement such model, all examples show only filtering and sorting of the already available items.</p>