2. PyQt6 按钮

import sys
from PyQt6.QtWidgets import QApplication, QMainWindow, QToolTip, QPushButton
from PyQt6.QtGui import QGuiApplication, QFont


class App(QMainWindow):

    def __init__(self):
        super().__init__()
        self.initUI()

    def initUI(self):
        self.setWindowTitle("PyQt6 窗口案例")

        QToolTip.setFont(QFont("SansSerif", 10))
        self.setToolTip("这是一个<b>QWidget</b>")

        btn = QPushButton("退出", self)
        btn.clicked.connect(QApplication.instance().quit)
        btn.move(100, 100)
        btn.setToolTip("这是一个Button")
        btn.resize(btn.sizeHint())

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

    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())