main.py

import sys
from PyQt5.QtWidgets import *
from PyQt5.QtCore import *
from PyQt5.QtGui import *

import windows


class App(QWidget):

    def __init__(self):
        super().__init__()
        self.title = 'PyQt5 simple window - pythonspot.com'
        self.left = 100
        self.top = 100
        self.width = 640
        self.height = 480
        self.initUI()

    def initUI(self):
        self.setWindowTitle(self.title)
        self.setGeometry(self.left, self.top, self.width, self.height)
        self.show()


if __name__ == '__main__':
    app = QApplication(sys.argv)
    MainWindows = QMainWindow()
    dialog = windows.Ui_Dialog()
    dialog.setupUi(MainWindows)
    MainWindows.show()
    sys.exit(app.exec_())