如何在PyQt5中相对于父窗口移动子窗口？

from PyQt5.QtWidgets import QApplication, QMainWindow, QDialog, QPushButton
from PyQt5.QtCore import Qt

class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("Main Window")
        self.setGeometry(100, 100, 300, 200)
        
        self.button = QPushButton("Open Dialog", self)
        self.button.clicked.connect(self.open_dialog)
        self.button.move(50, 50)
        
    def open_dialog(self):
        dialog = SubWindow(self)
        dialog.exec_()

class SubWindow(QDialog):
    def __init__(self, parent):
        super().__init__(parent)
        self.setWindowTitle("Sub Window")
        self.setGeometry(parent.x() + 50, parent.y() + 50, 200, 150)