import sys
from PyQt5.QtWidgets import QMainWindow, QAction, qApp, QPushButton, QLabel,QVBoxLayout, QMessageBox, QApplication
from PyQt5.QtGui import QIcon
class Window(QMainWindow):
    def __init__(self):
        super().__init__()
        self.initUI()
    def initUI(self):
        self.resize(300,300)
        self.menu=self.menuBar()
        fileMenu=self.menu.addMenu('File')
        exitAction=QAction(QIcon('aska_suck'), 'Exit', self)
        exitAction.triggered.connect(qApp.exit)
        fileMenu.addAction(exitAction)
        self.btn=QPushButton('kekos', self)
        self.btn.resize(self.btn.sizeHint())
        self.btn.move(150,150)
        self.btn.clicked.connect(self.createLayout)
        self.show()
    def createLayout(self):
        self.setWindowTitle('kekos')
        self.l=QLabel('kekos',self)
        self.l.move(200,200)
    def closeEvent(self, event):
        choice=QMessageBox.question(self,'kekos','vihod?',QMessageBox.Yes,QMessageBox.No)
        if choice==QMessageBox.Yes:
            event.accept()
        else:
            event.ignore()
app=QApplication(sys.argv)
w=Window()
sys.exit(app.exec_())

self.l.show()