如何在使用PyQt5打开新窗口时隐藏当前窗口

from PyQt5.QtWidgets import QApplication, QMainWindow, QPushButton, QWidget

class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        self.initUI()

    def initUI(self):
        self.setWindowTitle("主窗口")
        self.setGeometry(100, 100, 300, 200)

        self.button = QPushButton("打开新窗口", self)
        self.button.clicked.connect(self.openNewWindow)
        self.button.setGeometry(100, 100, 100, 30)

    def openNewWindow(self):
        self.hide()  # 隐藏当前窗口
        self.newWindow = NewWindow(self)
        self.newWindow.show()

class NewWindow(QWidget):
    def __init__(self, parent):
        super().__init__(parent)
        self.initUI()

    def initUI(self):
        self.setWindowTitle("新窗口")
        self.setGeometry(200, 200, 300, 200)

        self.button = QPushButton("返回主窗口", self)
        self.button.clicked.connect(self.returnToMainWindow)
        self.button.setGeometry(100, 100, 100, 30)

    def returnToMainWindow(self):
        self.parent().show()  # 显示主窗口
        self.close()  # 关闭当前窗口

if __name__ == "__main__":
    app = QApplication([])
    mainWindow = MainWindow()
    mainWindow.show()
    app.exec_()