code: def registerTopLevelWindow(self, window):
          
          # 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))
docs: Registers a top level window for this application.
          
          :param      window | <QtGui.QMainWindow>