title: How to implement the "exit" action in PyQt4?
body: <p>Many software have an "exit" action in the menubar items. I wonder know how to implement it in pyqt4.</p>
  
  <p>I think only invoking the method <code>QtCore.QCoreApplication.quit()</code> is not enough, because the application main window doesn’t disappear immediately when this method is called.</p>
  
  <p>I think in order to "exit", we shouldn’t only call the <code>quit()</code> method but also should close the application main window at the same time.</p>
  
  <p>What do you think ?</p>