title: Qml timer not triggered in the right interval
body: <p>I've created a timer QML app, and I'm using Timer qml component.
  The interval is set to 1000 milliseconds (the default one)... but it seems to be working properly only when the app is with focus on it.
  When I put it in background it seems that it's not triggered every time, and because of that I got some mistakes in the app.</p>
  
  <p>I've tried to find anything related to that in the documentation, but I couldn't
  The timer code is really simple:</p>
  
  <pre><code>Timer {
      id: timer
      repeat: true
      onTriggered: {msRemaining -= 1000; Core.secondsToText(type);}
  }
  </code></pre>
  
  <p>Anyone has any idea about that and how to fix it?</p>
  
  <p>Versions:
  Qt 5.2
  QML 2.0
  OS X 10.9</p>