title: multiple qml windows do not refresh properly on linux
body: <p>What I am trying to do is to create several qml windows and change their content via c++ (slots signals). The problem that occured to me now is that although the qml-content (like text) is updated but not properly redrawn.</p>
  
  <p>The result looks like this: <a href="http://i.stack.imgur.com/qfUr5.png" rel="nofollow">qml: 2 windows</a></p>
  
  <p>However, with only one window everything works perfectly fine.</p>
  
  <p>I am using Qt 5.5.0 + Xubuntu 14.04</p>
  
  <p>So the question is: How can I force these windows to refresh properly ?</p>
  
  <p>minimal example how to reproduce:</p>
  
  <p>main.cpp:</p>
  
  <pre><code>#include &lt;QGuiApplication&gt;
  #include &lt;QQmlApplicationEngine&gt;
  
  #include "myclass.h"
  
  int main(int argc, char *argv[])
  {
      QGuiApplication app(argc, argv);
  
      QQmlApplicationEngine engine;
      MyClass obj(engine);
  
      return app.exec();
  }
  </code></pre>
  
  <p>myclass.h:</p>
  
  <pre><code>#ifndef MYCLASS_H
  #define MYCLASS_H
  
  #include &lt;QObject&gt;
  #include &lt;QQmlApplicationEngine&gt;
  #include &lt;QQmlContext&gt;
  
  
  class MyClass : public QObject
  {
      Q_OBJECT
  public:
  
      explicit MyClass(QQmlApplicationEngine&amp; engine) : QObject()
      {
          engine.rootContext()-&gt;setContextProperty("myObj", this);
          engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
          engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
  
          startTimer(400);
      }
  
      void timerEvent(QTimerEvent *e)
      {
          static int i = 0;
          emit intIncreased(++i);
      }
  
  signals:
      void intIncreased(int myint);
  };
  
  #endif // MYCLASS_H
  </code></pre>
  
  <p>main.qml:</p>
  
  <pre><code>import QtQuick 2.5
  import QtQuick.Window 2.2
  
  Window {
      visible: true
  
      Connections {
          target: myObj
          onIntIncreased: myText.text = myint
      }
  
      Text {
          id: myText
          font.pixelSize: 100
          anchors.centerIn: parent
      }
  }
  </code></pre>
  
  <p>edit: works flawless on my Mac btw, so I guess it's a platform related issue.</p>