title: QML ListView spacing glitch
body: <p>I have a simple page in my application:</p>
  
  <pre><code>import QtQuick 2.5
  import QtQuick.Controls 2.0
  
  Page {
  
      ListView {
          anchors.fill: parent
          model: 50
          delegate: Item {
              clip: true
              height: 50
              anchors {
                  left: parent.left
                  right: parent.right
              }
  
              Rectangle {
                  color: "red"
                  anchors.fill: parent
              }
              Label {
                  text: index
              }
  
          }
      }
  
  }
  </code></pre>
  
  <p>Sometimes, when I'm scrolling, I see spacing between rows, yet spacing is zero. I suppose it's some kind of coordinates rounding error. I tracked down  possible source of the issue -- clip: true inside delegate. If I remove it, then everything is fine. </p>
  
  <p>Is it a bug of Qt, and how can I workaround it?</p>
  
  <p><a href="https://i.stack.imgur.com/Hrsrz.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Hrsrz.png" alt="enter image description here"></a></p>