PyQt5 QTableWidget右键单击单元格不会产生QMenu

from PyQt5.QtWidgets import QApplication, QMainWindow, QTableWidget, QMenu, QAction
from PyQt5.QtCore import Qt

class CustomTableWidget(QTableWidget):
    def __init__(self, parent=None):
        super().__init__(parent)
        
    def contextMenuEvent(self, event):
        menu = QMenu(self)
        
        # 添加菜单项
        action1 = QAction("菜单项1", self)
        action2 = QAction("菜单项2", self)
        menu.addAction(action1)
        menu.addAction(action2)
        
        # 显示菜单
        menu.exec_(event.globalPos())

class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        
        tableWidget = CustomTableWidget(self)
        self.setCentralWidget(tableWidget)
        
        # 添加表格数据
        tableWidget.setColumnCount(3)
        tableWidget.setRowCount(3)
        tableWidget.setItem(0, 0, QTableWidgetItem("单元格1"))
        tableWidget.setItem(0, 1, QTableWidgetItem("单元格2"))
        tableWidget.setItem(0, 2, QTableWidgetItem("单元格3"))
        
if __name__ == "__main__":
    app = QApplication([])
    mainWindow = MainWindow()
    mainWindow.show()
    app.exec_()