1. Import tkinter module

   import tkinter as tkfrom tkinter import *

   Note: Name of the module in Python 2.x is ‘Tkinter’ and in Python 3.x it is ‘tkinter’. Python 3.x is used here.
2. Import tkinter messagebox widget

   from tkinter import messagebox as mb

3. Create the method that is called to display the Yes/No Message Box

   def call():    res=mb.askquestion('Exit Application', 'Do you really want to exit')    if res == 'yes' :        root.destroy()    else :        mb.showinfo('Return', 'Returning to main application')

   Explanation:Syntax:

   askquestion(title=None, message=None, **options)

   Parameter
   • title: used to give a name which is displayed in as header of the dialog box.
   • message: question for the user.
   Return value:Returns 'yes' when the yes option is clicked and 'no' when the no option is clicked.Syntax:

   showinfo(title=None, message=None, **options)

   Parameter
   • title: used to give a name which is displayed in as header of the dialog box.
   • message: information for the user.
   Syntax:

   destroy()

   This method destroys a widget.
4. Create the canvas for the button will be placed

   root=tk.Tk()canvas=tk.Canvas(root, width=200, height=200)canvas.pack()

   Explanation:Syntax:

   Tk(screenName=None,  baseName=None,  className=’Tk’,  useTk=1)

   Used to create the parent window. Tk class is instantiated without any arguments.The name of the parent window can be changed to desired one by changing the value of className argument. Here 'root' is the parent window.Syntax:

   Canvas(master, option=value)

   Parameter:
   • master: used to represent the parent window.Here 'root' is the master.
   • option: used to specify border, background color, height, width etc .
   Return Value:The method returns a string (.!canvas) .Syntax:

   pack(**options)

   Organizes the widgets in blocks before placing in the parent widget.The options can be used to expand, fill and specify side(left, right, top, bottom)
5. Create the button and place it inside the canvas

   b=Button(root, text='Quit Application', command=call)canvas.create_window(100, 100, window=b)

   Explanation:Syntax:

   Button(master=None, options)

   Parameter:
   • master: Here root is the parent window.
   • options:There are a number of supported options. The options used in this case are text and command.
     • text:button text
     • command:the action or method that is to be invoked when the button is pressed.
   Return Value:The method returns a string (.!button) .Syntax:

   create_window(x, y, **options)

   Parameter:
   • x, y:Specifies the position of the widget(button) within the canvas.
   • options: There are a variety of options supported like anchor, height, width, state, tags, window. The option used here is window.
   • window:window=b where b is the widget(button) to be placed on the canvas.
   Return Value:Returns the object ID for the window object.
6. Call the mainloop() method

   root.mainloop()

   Explanation:Syntax:

   mainloop()

   It is an infinite loop that is called when the program is ready to be run.It waits for an event(mouse clicks) to occur and as soon as the event is received the event is processed.The mainloop() runs as long as the parent window is not destroyed.

# Python program to create# yes/no message boximporttkinterastkfromtkinterimport*fromtkinterimportmessageboxasmbdefcall():res=mb.askquestion('Exit Application','Do you really want to exit')ifres=='yes':root.destroy()else:mb.showinfo('Return','Returning to main application')# Driver's coderoot=tk.Tk()canvas=tk.Canvas(root,width=200,height=200)canvas.pack()b=Button(root,text='Quit Application',command=call)canvas.create_window(100,100,window=b)root.mainloop()

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