title: Why anchors.centerIn doesn't working for Column elements?
body: <p>I have this piece of QML code:</p>
  
  <pre><code> Column {
       spacing: units.gu(2)
       anchors {
           fill: parent
           centerIn: parent
       }
       Row {
           spacing: units.gu(4)
           ...
       }
       Row {
           spacing: units.gu(4)
           ...
       }
       Row {
           spacing: units.gu(4)
           ...
       }
       Row {
           spacing: units.gu(4)
           ...
       }
   }
  </code></pre>
  
  <p>I'm trying to center Column in its parent element (a Page element), but it doesn't work.
  If a try to <code>centerIn: parent</code> in one of the Rows, it works, but as I have 4 Rows, it break the layout. But Rows respond to this, instead my Column.</p>
  
  <p>Why make <code>centerIn: parent</code> works for Column? Theres another ways to center this?</p>