python PyQt组织菜单和工具栏

class Window(QMainWindow):
    # Snip...
    def _createMenuBar(self):
        # File menu
        # Snip...
        fileMenu.addAction(self.saveAction)
        # Adding a separator
        fileMenu.addSeparator()
        fileMenu.addAction(self.exitAction)
        # Edit menu
        # Snip...
        editMenu.addAction(self.cutAction)
        # Adding a separator
        editMenu.addSeparator()
        # Find and Replace submenu in the Edit menu
        findMenu = editMenu.addMenu("Find and Replace")
        # Snip...