PyQt:如何将选定的组合框值从QDialog传递到主窗口？

from PyQt5.QtWidgets import QApplication, QDialog, QComboBox, QVBoxLayout, QPushButton, QMainWindow

class Dialog(QDialog):
    def __init__(self, parent=None):
        super(Dialog, self).__init__(parent)
        self.setWindowTitle("Dialog")
        
        layout = QVBoxLayout()
        self.comboBox = QComboBox()
        self.comboBox.addItem("Option 1")
        self.comboBox.addItem("Option 2")
        self.comboBox.addItem("Option 3")
        layout.addWidget(self.comboBox)
        
        button = QPushButton("OK")
        button.clicked.connect(self.sendValue)
        layout.addWidget(button)
        
        self.setLayout(layout)
    
    def sendValue(self):
        selectedValue = self.comboBox.currentText()
        self.accept()  # 关闭对话框并返回结果
        self.emitValue(selectedValue)  # 发送信号
    
    def emitValue(self, value):
        self.valueEmitted.emit(value)  # 自定义的信号

class MainWindow(QMainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)
        self.setWindowTitle("Main Window")
        
        self.dialog = Dialog()
        self.dialog.valueEmitted.connect(self.handleValue)  # 连接信号和槽
        
        button = QPushButton("Open Dialog")
        button.clicked.connect(self.dialog.exec_)
        self.setCentralWidget(button)
    
    def handleValue(self, value):
        print("Selected value:", value)

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