title: QML: SequencialAnimation's running attribute set to false, but still running
body: <p>i made animations in transition. so if state change, so the transition is emitted. here is the sequential animation that i made. </p>
  
  <pre><code>SequentialAnimation{
              PropertyAnimation{
                  properties: "width"
                  duration: 300
              }
              PropertyAnimation{
                  properties: "x"
                  duration: 500
              }
              Component.onCompleted: {
                  var idx = Math.ceil(Math.random()*2);
                  if(idx===0){
                      anim0.running = true
                      anim1.running = false
                  }
                  else {
                      anim1.running = true
                      anim0.running = false
                  }
                  console.log("haha");
              }
          }
  
          SequentialAnimation{
              id: anim0
              running: false
              NumberAnimation{
                  running: anim0.running
                  properties: "x"
                  to: 300
                  duration: 500
              }
              Component.onCompleted: console.log("anim0");
          }
          SequentialAnimation{
              id: anim1
              running: false
              NumberAnimation{
                  running: anim1.running
                  properties: "x"
                  to: -300
                  duration: 500
              }
              Component.onCompleted: console.log("anim1");
          }
  </code></pre>
  
  <p>Ignore the JavaScript first on Component.onCompleted signal.
  SequencialAnimation with id: anim1 and anim0 keep running although i had already set running attribute to false...</p>