title: Qwidget window disappears
body: <p>Okay... This has been bugging me for hours. I have a qtmainwindow with a menubar.  I've managed to  connect an action in tje menubar to an independent Qwidget. But as soon as the Qwidget appears it disappears. I'm using the latest version of pyqt. </p>
  
  <p>Here's the code:</p>
  
  <pre><code>Import sys
  from PyQt4  import QtGui,  QtCore
  
  Class Main(QtGui.QtMainWindow) :
           def __init__(self) :
                 QtGui.QtMainWindow.__init__(self) 
                 self.setGeometry(300,300,240,320) 
                 self.show() 
  
                 menubar  = self. menuBar() 
  
                 filemenu = menubar. addMenu('&amp;File') 
  
                 new = QtGui.QAction(QtGui.QIcon('new.png'), 'New', self) 
                 new.triggered.connect(self.pop) 
                 filemenu.addAction(new) 
  
        def pop(self) :
              pop = Pop() 
  
  class Pop(QtGui.QWidget) :
           def __init__(self) :
                 QtGui.QWidget.__init__(self) 
                self.setGeometry(300,300,240,320&gt;
                self.setWindowTitle('Pop up') 
               self.show() 
  </code></pre>