title: How to set the style of the first/last item of QListWidget?
body: <p>I want to implement the following effect in a <em>QListWidget</em>:</p>
  
  <p><a href="https://i.stack.imgur.com/4u8AW.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/4u8AW.png" alt="enter image description here"></a></p>
  
  <p>Unfortunatelly, there is no <code>QListWidget::item:first</code> in the stylesheet of <em>QListWidget</em>.</p>
  
  <p>Ist there something like <code>css</code>'s brother selector <code>li~li</code> in <code>qss</code>? </p>
  
  <p>I have examined the <a href="http://doc.qt.io/qt-5/stylesheet-examples.html" rel="nofollow noreferrer">Qt Style example</a>, but the info there is not sufficient for me.</p>