title: Sliding OSX Dock type "sidebar" rather embedded QDockWidget type?
body: <p>I want to make a sliding "sidebar" similar to the functionality of the OSX "Dock" (e.g. mouse passes edge of screen and Dock slides out). I've been playing around with <code>QDockWidget</code> but since that is embedded in the window layout, it causes everything to shift when it becomes visible.</p>
  
  <p>Can someone suggest a way to implement this? </p>
  
  <ul>
  <li>Doesn't need to float (as a separate window/tool bar)</li>
  <li>Should scale to window height (e.g. window can be fullscreen or default size)</li>
  <li>Doesn't need to slide (animate) if that is complicated.</li>
  </ul>
  
  <p>I'm new to Qt and so don't want to over-think this. Is this just a matter of a custom widget or should I be looking at a borderless window? The custom widget approach seems right but I don't know how to specify that it overlay other window content and also scale if the window scales.</p>