PyQt5 keep window on top by clicking button

Question

I am trying to keep window by a Pin button. Here is the code:

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QVBoxLayout, QPushButton, QPushButton
from PyQt5 import QtCore

class App(QWidget):

    def __init__(self):
        super().__init__()
        self.title = 'Keep Going'
        self.width = 480
        self.height = 360
        self.initUI()


    def initUI(self):
        self.setWindowTitle(self.title)
        self.setFixedSize(self.width, self.height)
        self.layout = QVBoxLayout()
        self.button = QPushButton('PinTop')
        self.button.setCheckable(True)
        self.button.clicked.connect(self.winPinTop)
        self.layout.addWidget(self.button)
        # add tabs to widget
        self.setLayout(self.layout)
        self.show()


    def winPinTop(self):
        print('Pin')
        button = self.sender()
        if button.isChecked():
            print('on top')
            self.setWindowFlags(QtCore.Qt.WindowStaysOnTopHint)
            self.show()
        else:
            print('no top')
            self.setWindowFlags(self.windowFlags())
            self.show()


if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = App()
    sys.exit(app.exec_())

The window can not keep on top after clicking the button. I don't know how to fix this.

Infomation may help:

• Python 3.6.8
• PyQt version: 5.13.0
• Ubuntu 19.04

UPDATE
I replace QWidget with QMainWindow class to check this bug.

import sys
from PyQt5.QtWidgets import QMainWindow,QApplication, QWidget, QVBoxLayout, QPushButton, QPushButton
from PyQt5 import QtCore

class App(QMainWindow):

    def __init__(self):
        super().__init__()
        self.title = 'Keep Going'
        self.width = 480
        self.height = 360
        self.initUI()


    def initUI(self):
        self.setWindowTitle(self.title)
        win = QWidget()        
        win.setFixedSize(self.width, self.height)
        layout = QVBoxLayout()
        button = QPushButton('PinTop')
        button.setCheckable(True)
        button.clicked.connect(self.winPinTop)
        layout.addWidget(button)
        # add tabs to widget
        win.setLayout(layout)
        self.setCentralWidget(win)
        self.show()


    def winPinTop(self):
        print('Pin')
        button = self.sender()
        if button.isChecked():
            print('on top')
            self.setWindowFlags(QtCore.Qt.WindowStaysOnTopHint | QtCore.Qt.Dialog )
            print(self.windowFlags())
            self.show()
        else:
            print('no top')
            self.setWindowFlags(self.windowFlags() & ~QtCore.Qt.WindowStaysOnTopHint )
            print(self.windowFlags())
            self.show()


if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = App()
    sys.exit(app.exec_())

The problem is still here.

UPDATE 2019-9-11
After remove the show function. I can get the window on top.

def winPinTop(self):
    print('Pin')
    button = self.sender()
    if button.isChecked():
        print('on top')
        self.setWindowFlags(QtCore.Qt.WindowStaysOnTopHint | QtCore.Qt.Dialog )
        print(self.windowFlags())
        #self.show()
    else:
        print('no top')
        self.setWindowFlags(self.windowFlags() & ~QtCore.Qt.WindowStaysOnTopHint )
        print(self.windowFlags())
        #self.show()

But the window will close after I click the pin button. When I show this window, it stays on the top.
I don't know why this happened.

Reference: PyQt: Always on top