Pass Parent to Child Window in PyQt5 Mar 13th 2021 Words: 160

Here is an example of spawning a child window in the main window. The child window will be automatically destroyed on main window close. 

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import sys

from PyQt5.QtWidgets import QApplication, QMainWindow, QAction, QStatusBar, QDialog, QMenuBar


class MainWindow(QMainWindow):

    def __init__(self, *args, **kwargs):
        super(MainWindow, self).__init__(*args, **kwargs)
        self.setWindowTitle("My Fancy App")

        # Toolbar
        menu_bar = QMenuBar()

        self.window_about = AboutWindow(self)   # pass MainWindow instance as parent of AboutWindow
        button_action_about = QAction("About", self)
        button_action_about.setStatusTip("About this application")
        button_action_about.triggered.connect(self.on_button_action_about_click)
        menu_bar.addAction(button_action_about)

        self.setMenuBar(menu_bar)

        # Status bar
        self.setStatusBar(QStatusBar(self))

    def on_button_action_about_click(self):
        self.window_about.show()


class AboutWindow(QDialog):
    def __init__(self, *args, **kwargs):
        super(AboutWindow, self).__init__(*args, **kwargs)
        self.setWindowTitle("About")


if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = MainWindow()
    window.show()
    sys.exit(app.exec_())

Note the AboutWindow class in the child of QDialog, inherit from QWdget does not work. I dunno why though.