title: QWidget: Must construct a QApplication before a QPaintDevice
body: <p>First, I use Windows 7-64 bit with PyQwt5.2.0, PyQt4.5.4, NumPy1.3.0, python2.6.2 32-bit for compatibility reasons.</p>
  
  <p>While runnning my script this appears:</p>
  
  <pre><code>QWidget: Must construct a QApplication before a QPaintDevice
  </code></pre>
  
  <p>Surfing the net, looking for some way to fix it, I got that <code>QWidget</code> inherits <code>QObject</code> and <code>QPaintDevice</code> (and it is inherited bye almost every object I use), and <code>QMainWindow</code> inherits <code>QWidget</code>. I also got that some static function is trying to use some class, but I do not really understand what it means.</p>
  
  <p>If someone could please explain this, I would really appreciate it.</p>
  
  <p>PS: Sorry for any translation mistakes.</p>