python 3+ with tkinter: modal window not appearing - python-3.x

Question

I'm new to python. I'm trying to set up a GUI with a main window and a modal window to receive the database credentials. The main window has to be in the background when the modal window appears and the user should not interact with it. Actually the application should terminate in case the user fails to provide a valid username and password. I'm presenting part of the code here. What I get is the main window (the modal window does not appear at all) and I can't do anything but shut the program down - not directly; only through visual studio.
'''
import tkinter as tk
class login:
def checkDbCredentials(self, user, password):
if (len(user)<4 or len(password)<4):
return 0
return 1
def ok(self):
us = self.user.get()
pw = self.password.get()
if self.checkDbCredentials(us, pw)==0:
tk.messagebox.showinfo("Error", "Username and Password do not match")
sys.exit(0)
self.dic['user']=us
self.dic['pass']=pw
self.win2.destroy()
def cancel(self, event=None):
self.parent.focus_set()
self.destroy()
def widgets(self):
x = self.win2.winfo_screenwidth()
y = self.win2.winfo_screenheight()
xx = int((x-270)/2)
yy = int((y-85)/2)
geo = "270x85+" + str(xx) + "+" + str(yy)
self.win2.geometry(newGeometry=geo)
self.tempLab= tk.Label(self.win2, text="Username:", pady=5)
self.tempLab1 = tk.Label(self.win2, text="Password:")
self.iuser = tk.Entry(self.win2, textvariable = self.user, width=30)
self.ipass = tk.Entry(self.win2, textvariable = self.password, width=30, show="*")
self.tempLab.grid(column=0, row=0)
self.tempLab1.grid(column=0, row=1)
self.iuser.grid(column=1, row=0)
self.ipass.grid(column=1, row=1)
self.bt = tk.Button(self.win2, text="Submit", command=lambda: self.ok())
self.bt.grid(column=0, row=2, columnspan=2, pady=5)
self.win2.bind("<Return>", self.ok)
self.win2.bind("<Escape>", self.cancel)
def __init__(self, dic, parent):
self.win2 = tk.Toplevel(parent)
self.parent=parent
self.dic = dic
self.user = tk.StringVar()
self.password = tk.StringVar()
self.win2.overrideredirect(1)
self.widgets()
self.win2.transient(parent)
self.win2.grab_set()
self.win2.protocol("WM_DELETE_WINDOW", self.cancel)
self.parent.wait_window(self.win2)
And the main class code is the following:
import tkinter as tk
from tkinter import ttk, X, Y, BOTH
from tkinter import messagebox
import sys
import login
class mainWindow:
def connect(bt, fr):
notImplementedYet()
def notImplementedYet():
msg = tk.messagebox
msg.showinfo("Warning", "Not Implemented yet!")
btX = 20
btY = 5
btSunken = '#aec2c2' # sunken button color
btRaised = '#85adad' # normal button color
rw = 0 # starting row for buttons
cl = 0 # starting column
dbCredentials = {"user":"", "pass":""}
win = tk.Tk()
win.title("Title")
win.geometry(newGeometry="1366x700+00+00")
win.iconbitmap(bitmap="bitmap.ico")
fr1 = tk.Frame(win, width=1366, height=50, background='beige')
fr1.grid(column=cl, row=rw, rowspan=5)
fr2 = tk.Frame(win)
fr2.grid(column=0, row=1)
lb2 = tk.Label(fr2, text="frame 2", background=btRaised)
btConnect = tk.Button(fr1, text="Connect", background = btRaised ,command=lambda: connect(btConnect, fr1), width=btX, height=btY)
btConnect.grid(column=0, row=0)
log = login.login(dbCredentials, win)
win.wait_window(log.win2)
print(dbCredentials)
win.mainloop()
win = mainWindow()
The question is why is the modal window not appearing? I've tried placing the 'wait_window' in the other class as well but it's still not working.