Returns a list of the top level windows for this application.
        
        :return     [<QtGui.QMainWindow>, ..]

def topLevelWindows(self):
        """
        Returns a list of the top level windows for this application.
        
        :return     [<QtGui.QMainWindow>, ..]
        """
        out = []
        clean = []
        for ref in self._topLevelWindows:
            window = ref()
            if window is not None:
                clean.append(ref)
                out.append(window)

        self._topLevelWindows = clean
        return out