30. PyQt6 QComboBox

import sys
from PyQt6.QtWidgets import QApplication, QMainWindow, QLabel, QComboBox
from PyQt6.QtGui import QGuiApplication


class App(QMainWindow):

    def __init__(self):
        super().__init__()
        self.lbl = None
        self.initUI()

    def initUI(self):
        self.setWindowTitle("PyQt6 QComboBox")

        self.lbl = QLabel("Ubuntu", self)
        combo = QComboBox(self)
        combo.addItem("Ubuntu")
        combo.addItem("Mandriva")
        combo.addItem("Fedora")
        combo.addItem("Arch")
        combo.addItem("Gentoo")
        combo.move(50, 50)

        combo.textActivated[str].connect(self.onActivated)

        self.setGeometry(100, 100, 400, 300)
        self.center()

    def onActivated(self, text):
        self.lbl.setText(text)
        self.lbl.adjustSize()

    def center(self):
        qr = self.frameGeometry()
        cp = QGuiApplication.primaryScreen().availableGeometry().center()
        qr.moveCenter(cp)
        self.move(qr.topLeft())


if __name__ == "__main__":
    app = QApplication(sys.argv)
    cls_app = App()
    cls_app.show()
    sys.exit(app.exec())