QMainWindow

class QMainWindow

Menu

#!/usr/bin/python3

import sys
from PyQt5.QtWidgets import QMainWindow, QAction, qApp, QApplication
from PyQt5.QtGui import QIcon

"""
QMainWindow includes a menu bar, a tool bar and a status bar
"""

class Menu(QMainWindow):

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

    newAct = QAction(QIcon.fromTheme('application-new'), '&New', self)
    newAct.setShortcut('Ctrl+N')
    newAct.setStatusTip('New Something')
    newAct.triggered.connect(self.new)

    exitAct = QAction(QIcon.fromTheme('application-exit'), '&Exit', self)
    exitAct.setShortcut('Ctrl+Q')
    exitAct.setStatusTip('Exit application')
    exitAct.triggered.connect(qApp.quit)

    self.statusBar()

    menubar = self.menuBar()
    fileMenu = menubar.addMenu('&File')
    fileMenu.addAction(newAct)
    fileMenu.addAction(exitAct)

    self.setGeometry(300, 300, 300, 200)
    self.setWindowTitle('Menu')
    self.show()

  def new(self):
    print('New Something')

app = QApplication(sys.argv)
ex = Menu()
sys.exit(app.exec_())

SubMenu

#!/usr/bin/env python3

import sys
from PyQt5.QtWidgets import QMainWindow, QAction, QMenu, qApp, QApplication
from PyQt5.QtGui import QIcon

class SubMenu(QMainWindow):

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

    menubar = self.menuBar()
    fileMenu = menubar.addMenu('File')

    newAct = QAction(QIcon.fromTheme('document-new'), '&New', self)
    newAct.setShortcut('Ctrl+N')
    newAct.setStatusTip('New Something')
    newAct.triggered.connect(self.new)

    exitAct = QAction(QIcon.fromTheme('application-exit'), '&Exit', self)
    exitAct.setShortcut('Ctrl+Q')
    exitAct.setStatusTip('Exit application')
    exitAct.triggered.connect(qApp.quit)

    mailMenu = QMenu('Mail', self)
    mailAct = QAction(QIcon.fromTheme('mail-send-receive'),'Import mail', self)
    mailMenu.addAction(mailAct)
    mailAct.triggered.connect(self.getMail)


    fileMenu.addAction(newAct)
    fileMenu.addMenu(mailMenu)
    fileMenu.addAction(exitAct)

    self.setGeometry(300, 300, 300, 200)
    self.setWindowTitle('Submenu')
    self.show()

  def new(self):
    print('New Something')

  def getMail(self):
    print('Getting Mail')

app = QApplication(sys.argv)
ex = SubMenu()
sys.exit(app.exec_())