Registers a top level window for this application.
        
        :param      window | <QtGui.QMainWindow>

def registerTopLevelWindow(self, window):
        """
        Registers a top level window for this application.
        
        :param      window | <QtGui.QMainWindow>
        """
        # set the main window for this instance
        if not self._topLevelWindows:
            self.setPalette(window.palette())
            self.setWindowIcon(window.windowIcon())
            
            if self.splash():
                self.splash().finish(window)
        
        self._topLevelWindows.append(weakref.ref(window))