from tkinter import (BOTH, END, BOTTOM, DISABLED, NORMAL, 
                    Tk, Frame, Menu, Button, Label, Text, Toplevel, Message, 
                    StringVar, IntVar)
import subprocess as sub


class App(Frame):

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

        self.initUI()


    def initUI(self):
        self.master.title("Centered window")
        self.pack()
        self.centerWindow()


        menubar = Menu(self.master)
        self.master.config(menu=menubar)

        fileMenu = Menu(menubar, tearoff=0)
        fileMenu.add_command(label="ipconfig", command=self.ipconfig)
        fileMenu.add_separator()
        fileMenu.add_command(label="Exit", command=self.onExit)
        menubar.add_cascade(label="File", menu=fileMenu)

        helpMenu = Menu(menubar, tearoff=0)
        menubar.add_cascade(label="Help",  menu=helpMenu)
        helpMenu.add_command(label="About", state=NORMAL, command=self.HelpAbout)


    def centerWindow(self):
        w = 804
        h = 280

        sw = self.master.winfo_screenwidth()
        sh = self.master.winfo_screenheight()

        x = (sw - w)/2
        y = (sh - h)/2
        self.master.geometry('%dx%d+%d+%d' % (w, h, x, y))

    def HelpAbout(self):
        self.topHelp = Toplevel(self.master)
        print(str(self.topHelp.winfo_exists()))
        
        self.topHelp.title("###")
        self.MsgHelp = Message(self.topHelp)
        self.MsgHelp.pack()
        self.MsgHelp.config(text="bla bla bla")

        self.btHelp = Button(self.topHelp, text="bye", command=self.topHelp.destroy)
        self.btHelp.pack()
 
    def ipconfig(self):
      
        p = sub.Popen('ipconfig', shell=True, stdout=sub.PIPE, stderr=sub.PIPE)
        output, errors = p.communicate()
        print (output)


    def onExit(self):
        self.quit()


def main():

    root = Tk()
    root.resizable(0, 0)        #block resize window
    ex = App()
    root.mainloop()


if __name__ == '__main__':
    main()