title: QML FileDialog issue
body: <p>I am trying to use the <code>FileDialog</code> component in QML.</p>
  
  <p>I have done exactly the same code that is in the Qt documentation at the link <a href="http://doc.qt.io/qt-5/qml-qtquick-dialogs-filedialog.html" rel="nofollow">http://doc.qt.io/qt-5/qml-qtquick-dialogs-filedialog.html</a> and it does not show the dialog and returns the error: <code>QFileInfo::absolutePath: Constructed with empty filename</code>. I tried to write a simple code to test it and the return was the same error. My code is below.</p>
  
  <pre><code>import QtQuick 2.4
  import QtQuick.Window 2.2
  import QtQuick.Controls 1.3
  import QtQuick.Dialogs 1.2
  
  Window {
      visible: true
  
      width: 360
      height: 640
  
      maximumHeight: 640
      minimumHeight: 640
  
      maximumWidth: 360
      minimumWidth: 360
  
      title: "Acessar Galeria Test"
  
      Rectangle {
          id: principal
  
          anchors.fill: parent
  
          FileDialog {
              id: fileDialog
  
              title: "Please choose a file"
  
              folder: shortcuts.home
  
              visible: true
          }
      }
  }
  </code></pre>