title: qt: invalid property name 'x' (M16) for button
body: <p>I'm using Qt 5.4.1 in QtCreator 3.3.1</p>
  
  <p>I've imported QtQuick.Controls 1.2 into my QML and added a series of buttons:</p>
  
  <pre><code>Rectangle {
      id: buttonBar
      x: 480
      y: 0
      width: 320
      height: 80
      Button {
          x: 0
          y: 0
  
          width: 80
          height: 60
  
          text: "Songs"
      }
  
      Button {
          x: 80
          y: 0
  
          width: 80
          height: 60
  
          text: "Artists"
      }
  
      Button {
          x: 160
          y: 0
  
          width: 80
          height: 60
  
          text: "Albums"
      }
  
      Button {
          x: 240
          y: 0
  
          width: 80
          height: 60
  
          text: "Back"
      }
  }
  </code></pre>
  
  <p>They all render fine when I run the program, but everytime that QtCreator opens the qml file it jumps into design mode and I get the warning:</p>
  
  <pre><code>invalid property name 'x' (M16) 
  </code></pre>
  
  <p>and the lines where I use x, y, width and height are all underlined when I view the file in edit mode.</p>
  
  <p>But the documentation says these are valid properties for my buttons - <a href="http://doc.qt.io/qt-5/qml-qtquick-controls-button-members.html" rel="noreferrer">http://doc.qt.io/qt-5/qml-qtquick-controls-button-members.html</a></p>
  
  <p>How do I stop/resolve this error message?</p>