PyQt5 QMainwindow poped but hide

Question

I got a problem with this code:

note that i created esquisseUi with Qt Designer and pyuic5

import sys

from PyQt5.QtWidgets import QApplication, QMainWindow, QMessageBox

from esquisseUi import *


class VueEsquisse(QMainWindow):

    def __init__(self):
        super(QMainWindow, self).__init__()
        self.ui = Ui_MainWindow()
        self.ui.setupUi(self)


class ControleEsquisse:

    def __init__(self):
        self.vue = VueEsquisse()
        self.vue.show()


if __name__ == "__main__":
    app = QApplication(sys.argv)
    ControleEsquisse()
    sys.exit(app.exec_())

The Mainwindow poped but hide automatically.

It is the same structure that i use for a previous program that worked fine!

I don't understand because in debug mode with step by step the window appears and keep visible.