title: Qt QCursor::setPos() does nothing
body: <p>I've created a minimal class to demonstrate my problem. I'm trying to set the cursor position, but it shows no effect. In my example class I try to center the cursor to the widget. 
  Here is my class:</p>
  
  <pre><code>class testWidget : public QWidget
  {
      Q_OBJECT
  public:
      testWidget();
  protected:
      virtual void mouseMoveEvent(QMouseEvent* event);
  };
  </code></pre>
  
  <p>And here is the implementation:</p>
  
  <pre><code>testWidget::testWidget()
  {
      setMinimumSize(800,600);
      show();
  }
  
  void testWidget::mouseMoveEvent(QMouseEvent *event)
  {
      QPoint before(mapFromGlobal(QCursor::pos()));
      QPoint center = mapToGlobal(QPoint(width()/2,height()/2));
      QCursor::setPos(center);
      qDebug()&lt;&lt;"Before:"&lt;&lt;before&lt;&lt;"After:"&lt;&lt;mapFromGlobal(QCursor::pos());
  }
  </code></pre>
  
  <p>When moving the mouse cursor while pressing a mouse button I get the following output (exmaple):</p>
  
  <blockquote>
    <p>Before: QPoint(754,48) After: QPoint(400,300)</p>
  </blockquote>
  
  <p>This means before I called QCursor::setPos(center) the cursor is at the position 754;48 which is in the top-right corner of the widget. After I set the cursor-position with QCursor::setPosition(center) the cursor should be at the center of the widget, which it is not, the cursor stays in the top-right corner. And to my further confusion, QCursor::pos() returns the center of the widget, even though the cursor is not at the center.</p>
  
  <p>Any hints would be much appreciated.</p>
  
  <p>Thank you for your time...</p>