Python QtGui Calendar Widget Call button

I am using a calendar widget for Python. And I need to call the widget when a button is clicked. The situation is that I cannot find what is the method in the calendar class that displays the widget itself. The calendar class was taken from here: http://www.eurion.net/python-snippets/snippet/Calendar_Date%20picker.html

Here are my imports:

from tkinter import *
from tkinter import ttk
import tkinter.messagebox
import time
import requests #needs to be installed
import pymysql #needs to be installed
import csv 
import win32com.client #needs to be installed
from calendar import Calendar
import datetime

Here is the button creation:

# Calendar Buttons
calBut=ttk.Button(f2, width=4, text="Cal",       command=Calendar.what_method?).grid(column=3,row=1, sticky=W)

As far as I know, I can just set the command of the button to call the widget display method located in the calendar class. How to get the method that displays the calendar widget each time my button is clicked? None of the ones showing are displaying the widget.

Using Python 3.3.5 Spider WinPython 3.3.5

**EDIT**

The program has tabs and the f2 indicates the tab where the button will be.

from tkinter import *
from tkinter import ttk
import tkinter.messagebox
import time
import requests #needs to be installed
import pymysql #needs to be installed
import csv 
import win32com.client #needs to be installed
import datetime
from calendar import Calendar
import calendar


#################################
# Create Button Click Calendar

 def callback():
    root2=Toplevel(f2)
    ttkcal = Calendar(root2,firstweekday=calendar.SUNDAY)
    ttkcal.pack(expand=1, fill='both')
    root2.update()
    root2.minsize(root2.winfo_reqwidth(), root2.winfo_reqheight())



 # Calendar Buttons

 b=ttk.Button(f2, width=4, text="Cal", command=callback).grid(column=3,row=1, sticky=W)

When I press the button, it opens the calendar window, but it is empty. And the console gives me error:

TypeError: __init__() got multiple values for argument 'firstweekday

Thank you

Not so easy. The problem is that you mix the two GUI libraries. Therefore it is necessary two main event loops (at least): one for Tkinter code and one for PyQt code.
One way to do what you want - using subprocess and threading modules to run calendar.py in different thread. Example:

from tkinter import *
from tkinter import ttk

import subprocess
import threading

master = Tk()

def callback():
    subprocess.call('python calendar.py')


b=ttk.Button(master, width=4, text="Cal", command=lambda:threading.Thread(target=callback).start()).grid(column=3,row=1, sticky=W)


mainloop()

Another way - creating Qt main event loop inside callback function (dirty solution):

from tkinter import *
from tkinter import ttk
from calendar import Calendar
import sys
from PyQt4 import QtGui

master = Tk()

def callback():
    app = QtGui.QApplication(sys.argv)
    gui = Calendar()
    gui.show()
    app.exec_()


b=ttk.Button(master, width=4, text="Cal", command=callback).grid(column=3,row=1, sticky=W)

mainloop()

EDIT: How to call widget. First of all, look at this answer, and modify your ttkcalendar.py as kalgasnik suggested. Then try this:

from tkinter import *
from tkinter import ttk
from ttkcalendar import Calendar
import calendar

master = Tk()

def callback():
    root2=Toplevel(master)
    ttkcal = Calendar(root2,firstweekday=calendar.SUNDAY)
    ttkcal.pack(expand=1, fill='both')
    root2.update()
    root2.minsize(root2.winfo_reqwidth(), root2.winfo_reqheight())

b=ttk.Button(master, width=4, text="Cal", command=callback).grid(column=3,row=1, sticky=W)

mainloop()

EDIT 2. Solving the problems
Ok, it seems I found all problems.

Actually, you import twice the same module - standard calendar module:
```
from calendar import Calendar
import calendar
```

But you do not import the class Calendar from ttkcalendar module (Do not forget to change it as described here). So, import should look like this:

import ttkcalendar
import calendar

Creating calendar (I changed the code a bit for clarity):

ttkcal = ttkcalendar.Calendar(root2,firstweekday=calendar.SUNDAY)

In your code, the main window is initialized twice:
line 15: master = Tk()
line 960: root = Tk()
You need to remove the first initialization.
You mix pack() and grid() in the same master window. According the docs, it is a bad idea:

Warning: Never mix grid and pack in the same master window. Tkinter will happily spend the rest of your lifetime trying to negotiate a solution that both managers are happy with. Instead of waiting, kill the application, and take another look at your code. A common mistake is to use the wrong parent for some of the widgets.

So, instead nb.pack(fill='both', expand='yes') you have to write something like this nb.grid(column=0, row=0, sticky=(W, E))

Finally, here are links to the fixed code:

ttkcalendar.py (already modified, ready to use):
https://gist.github.com/anonymous/5e0d973f57e185572df2

Your script with described modifications:
https://gist.github.com/anonymous/65cb808dc64e414c0c12