diff --git a/learning_python3_gui.md b/learning_python3_gui.md
index 5858827..3b295d8 100644
--- a/learning_python3_gui.md
+++ b/learning_python3_gui.md
@@ -3,134 +3,134 @@
 ## Tkinter helloworld
 
 The absolute most basic way to have a *hello world* GUI program up and running with Tkinter is the following.
+It creates an *application*, sets the *title* as `hello world` and enters the **main eventloop**.
 
 ```python
-from tkinter import *
+import tkinter as tk
 
-root = Tk()
-
-MyLabel = Label(root,text="hello world")
-MyLabel.pack()
+root = tk.Tk()
+root.title("hello world")
 
 root.mainloop()
 ```
-Tkinter have two popular architectures, the Tcl and Tk. This two architectures are different, they have their own functionality and their own official documentation. 
-We are gonna use the Tk architecture.
 
-The Tk architecture is used to create a GUI widget. He adds a lot of custom commands, so the widget is very customizable. 
+Tkinter has two popular architectures, Tcl and Tk.
+These two architectures are quite different as they each have their own functionality and their own official documentation. 
+We are going use the Tk architecture.
 
-In the previous code,the `mainloop()` instruction allows us to open the main window and to not close immediately the window.
-And then, the `Label()` method creates label in a layout. This method has many parameters to customize a label. The instruction `pack()` will be always call , this instruction can 
-add and adjust a widget. 
+The Tk architecture is used to create a GUI widget which has a lot of **methods** and **attributes** so it's quite customizable.
+
+In the previous code,the `mainloop()` method allows us to open the main window and to not close the window immediately .
+This **event loop** will process all mouse event, button clicks, and changes.
 
 While it works we know better by now.
-We should include the `if __name__ == "__main__"` statement.
+We should include the `if __name__ == "__main__"` statement so let's do this!
 
 ```python
-from tkinter import *
-if __name__ == "__main__":
-    root = Tk()
+import tkinter as tk
 
-    MyLabel = Label(root,text="hello world")
-    MyLabel.pack()
+if __name__ == "__main__":
+    root = tk.Tk()
+    root.title("hello world")
 
     root.mainloop()
 ```
 
-The instance of `Tk()` is what will actually process our event loop and the `root` is the content of our window. We can customize `root` with instruction like geometry, title,etc.
-In the latter we will create our button and labels so should create our own class and inherit from it.
+The instance of `tk.Tk()` is what will actually process our event loop and the `root` is the content of our window. We can customize `root` with instruction like geometry, title, etc.
+To this instance we can attach other widgets and display them.
 
 ```python
-from tkinter import *
+import tkinter as tk
 
-class MainWindow(Frame):
+
+class Application(tk.Tk):
     def __init__(self):
-        Label.__init__(self, text="hello world")
-        self.pack()
+        tk.Tk.__init__(self)
+        self.title("hello world")
+        self.geometry("500x400")
+
 
 if __name__ == "__main__":
-    root = Tk()
-    root.title("title of the window") 
-    root.geometry("500x300")
-    MainWindow()
-    root.mainloop()
+    app = Application()
+    app.mainloop()
 ```
 
-We can add content to the *frame*, such as labels, input boxes and buttons as follows.
+We can add content to this window, such as labels, input boxes and buttons as follows.
 
 
 ```python
-from tkinter import *
+import tkinter as tk
 
-class MainWindow(Frame):
+
+class Application(tk.Tk):
     def __init__(self):
-        Label.__init__(self, text="hello world")
-        #Label
-        MyLabel = Label(self, text="This is a label")
-        MyLabel.pack()
+        tk.Tk.__init__(self)
+        self.title("hello world")
+        self.geometry("500x400")
+        self.resizable(0, 0)
+        self.label = tk.Label(self, text="This is a label", bg="yellow")
+        self.label.pack()
 
-        self.config(bg="yellow")
-        self.pack()
 
 if __name__ == "__main__":
-    root = Tk()
-    root.title("title of the window")
-    root.geometry("500x300")
-    MainWindow()
-    root.mainloop()
+    app = Application()
+    app.mainloop()
 ```
 
-Let's try to put multiple visual object into the same frame.
+Let's try to put multiple visual object into the same window.
 
 ```python3
-from tkinter import *
+import tkinter as tk
 
-class MainWindow(Frame):
+
+class Application(tk.Tk):
     def __init__(self):
-        Label.__init__(self, text="hello world")
-        #Label
-        MyLabel = Label(self, text="This is a label")
-        MyLabel.pack()
-        #Button
-        MyButton = Button(self, text="I'm clickable!")
-        MyButton.pack()
-        
-        self.config(bg="yellow")
-        self.pack()
+        tk.Tk.__init__(self)
+        self.title("hello world")
+        self.geometry("500x400")
+        self.label = tk.Label(text="This is a label")
+        self.label.pack()
+
+        self.button = tk.Button(text="I'm clickable!")
+        self.button.pack()
+
+        self.output = tk.Label(text="I'm a second label")
+        self.output.pack()
+
 
 if __name__ == "__main__":
-    root = Tk()
-    root.title("title of the window")
-    root.geometry("500x300")
-    MainWindow()
-    root.mainloop()
+    app = Application()
+    app.mainloop()
 ```
 
 You see how they are *stacked* one on top of the other?
-We can overcome this problem with parameters of [pack()](https://wxpython.org/Phoenix/docs/html/sizers_overview.html). 
-We can also use other geometry managers like [grid()](https://www.pythontutorial.net/tkinter/tkinter-grid/) and [place()](https://www.pythontutorial.net/tkinter/tkinter-place/).
+We can overcome this problem with parameters of [pack()](https://wxpython.org/Phoenix/docs/html/sizers_overview.html) or we can use other geometry managers like [grid()](https://www.pythontutorial.net/tkinter/tkinter-grid/) and [place()](https://www.pythontutorial.net/tkinter/tkinter-place/).
 
 ```python
-from tkinter import *
+import tkinter as tk
 
-class MainWindow(Frame):
+
+class Application(tk.Tk):
     def __init__(self):
-        Frame.__init__(self, master=None)
-        MyPanel = PanedWindow.__init__(self, bg="Blue")
-        #Label
-        MyLabel = Label(MyPanel, text="this is a label", bg= "yellow")
-        MyLabel.pack(fill="x")
-        #Bouton
-        MyButton = Button(MyPanel, text="I'm clickable!")
-        MyButton.place(x=10, y=50)
-        self.pack(fill=BOTH,expand=True)
+        tk.Tk.__init__(self)
+        self.title("hello world")
+        self.geometry("500x400")
+        self.resizable(0, 0)
+        self.label = tk.Label(self, text="This is a label", bg="yellow")
+        self.label.grid(column=0, row=0, sticky=tk.W, padx=5, pady=5)
+
+        self.button = tk.Button(self, text="I'm clickable!")
+        self.button.grid(column=1, row=0, sticky=tk.E, padx=5, pady=5)
+
+        self.output = tk.Label(self, text="I'm a second label")
+        self.output.grid(column=1, row=1, sticky=tk.E, padx=5, pady=5)
+
+        self.config(bg="yellow")
+
 
 if __name__ == "__main__":
-    root = Tk()
-    root.title("this is the title of the window") 
-    root.geometry("500x300") 
-    win = MainWindow()
-    root.mainloop()
+    app = Application()
+    app.mainloop()
 ```
 
 This is looking better!
@@ -152,137 +152,179 @@ Each time we click the button, that method will be called.
 Because it is a *method* it has access to *self* so it can modify *anything* within the scope of the instance.
 
 ```python
-from tkinter import *
-class MainWindow(Frame):
-    def __init__(self): 
-        Frame.__init__(self, master=None)
-        MyPanel = PanedWindow.__init__(self, bg="Blue")
-        #Label
-        MyLabel = Label(MyPanel, text="this is a label", bg= "yellow")
-        MyLabel.pack(fill="x")
-        #Bouton
-        MyButton = Button(MyPanel, text="I'm clickable!", command=lambda  : self.ButtonEnable(MyLabel))
-        MyButton.place(x=10, y=50)
-        self.pack(fill=BOTH,expand=True) 
-        
-    def ButtonEnable(self, Label):
-        global number
-        number += 1
-        counter = "You have press the button {} time".format(number)
-        Label.config(text=counter)
+import tkinter as tk
 
 
-number=0
+class Application(tk.Tk):
+    def __init__(self):
+        tk.Tk.__init__(self)
+        self.title("hello world")
+        self.geometry("500x400")
+        self.resizable(0, 0)
+        self.label = tk.Label(self, text="This is a label", bg="yellow")
+        self.label.pack()
 
-if __name__ == "__main__":
-    root = Tk()
-    root.title("this is the title of the window") 
-    root.geometry("500x300") 
-    win = MainWindow()
-    root.mainloop()
+        self.button = tk.Button(self, text="I'm clickable!", command=self.clicked)
+        self.button.pack()
 
+        self.output = tk.Label(self, text="I'm a second label")
+        self.output.pack()
 
-```
+        self.config(bg="yellow")
 
-We can use the same *idea* to grab input from the textbox.
-
-```python
-from tkinter import *
-
-class MainWindow(Frame):
-    def __init__(self): 
-        Frame.__init__(self, master=None)
-        MyPanel = PanedWindow.__init__(self, bg="Blue")
-        #Label
-        MyLabel = Label(MyPanel, text="this is a label", bg= "yellow")
-        MyLabel.pack(fill="x")
-        #TextBox
-        MyEntry = Entry(MyPanel)
-        MyEntry.place(x=200,y=50)
-        #Bouton
-        MyButton = Button(MyPanel, text="I'm clickable!", command=lambda  : self.ButtonEnable(MyLabel,MyEntry))
-        MyButton.place(x=10, y=50)
-        self.pack(fill=BOTH,expand=True) 
-
-
-    def ButtonEnable(self, MyLabel, MyEntry):
-        MyText = MyEntry.get()
-        MyLabel.config(text=MyText)
+    def clicked(self):
+        print("hello world!")
 
 
 if __name__ == "__main__":
-    root = Tk()
-    root.title("this is the title of the window")
-    root.geometry("500x300") 
-    win = MainWindow()
-    root.mainloop()
-
-
+    app = Application()
+    app.mainloop()
 ```
 
-## Tkinter guess the number
+We can see *hello world!* printed to the console with each click!
+As we're using a `class` we have *access* to the instance of the application so we can use the `self.output` label to show our messages.
 
 ```python
-import time
-from tkinter import *
+import tkinter as tk
+
+
+class Application(tk.Tk):
+    def __init__(self):
+        tk.Tk.__init__(self)
+        self.title("hello world")
+        self.geometry("500x400")
+        self.resizable(0, 0)
+        self.label = tk.Label(self, text="This is a label", bg="yellow")
+        self.label.pack()
+
+        self.button = tk.Button(self, text="I'm clickable!", command=self.clicked)
+        self.button.pack()
+
+        self.output = tk.Label(self, text="I'm a second label")
+        self.output.pack()
+
+        self.config(bg="yellow")
+        self.counter = 0
+
+    def clicked(self):
+        self.counter += 1
+        self.output.config(text="butter has been clicked {} times".format(self.counter))
+
+
+if __name__ == "__main__":
+    app = Application()
+    app.mainloop()
+```
+
+🏃 Try it
+---
+
+We can use the same *idea* to grab input from the input boxes called `tk.Entry`.
+The code below *adds* two numbers but it's not working properly.
+Can you fix it for me please?
+
+```python
+import tkinter as tk
+
+
+class Application(tk.Tk):
+    def __init__(self):
+        tk.Tk.__init__(self)
+        self.title("hello world")
+        self.geometry("500x400")
+        self.resizable(0, 0)
+        self.label_one = tk.Label(self, text="Number 1:", bg="yellow")
+        self.label_one.grid(column=0, row=0, sticky=tk.W, padx=5, pady=5)
+
+        self.label_two = tk.Label(self, text="Number 2:", bg="yellow")
+        self.label_two.grid(column=0, row=1, sticky=tk.W, padx=5, pady=5)
+
+        self.input_one = tk.Entry(self)
+        self.input_one.grid(column=1, row=0, sticky=tk.W, padx=5, pady=5)
+        self.input_two = tk.Entry(self)
+        self.input_two.grid(column=1, row=1, sticky=tk.W, padx=5, pady=5)
+
+        self.button = tk.Button(self, text="add two numbers", command=self.clicked)
+        self.button.grid(column=0, row=3, sticky=tk.W, padx=5, pady=5)
+
+        self.output = tk.Label(self, text="...")
+        self.output.grid(column=1, row=3, sticky=tk.W, padx=5, pady=5)
+
+        self.config(bg="yellow")
+
+    def clicked(self):
+        number_one = self.input_one.get()
+        number_two = self.input_two.get()
+        total = number_one + number_two
+        self.output.config(text="sum: {}".format(total))
+
+
+if __name__ == "__main__":
+    app = Application()
+    app.mainloop()
+```
+
+# Coding challenge - Guess the number
+
+Can you code me a *guess the number* game but using `tkinter`?
+
+<details>
+<summary>Spoiler warning</summary>
+
+```python
+import tkinter as tk
 import random
 
-class MainWindow(Frame):
+
+class Application(tk.Tk):
     def __init__(self):
-        Frame.__init__(self, master=None, bg="white")
-        MyPanel = PanedWindow.__init__(self)
+        tk.Tk.__init__(self)
+        self.title("hello world")
+        self.geometry("500x400")
+        self.resizable(0, 0)
 
-        MyNumber = random.randint(0, 100)
+        self.number = random.randint(0, 10)
 
-        #Label
-        self.MyLabel = Label(MyPanel, text="I have a number in mind...", bg= "blue")
-        self.MyLabel.pack(fill="x", ipadx=25, ipady=20)
-        #TextBox
-        MyEntry = Entry(MyPanel)
-        MyEntry.place(x=200,y=90)
-        #Bouton
-        MyButton = Button(MyPanel, text="I'm clickable!", command=lambda  : self.ButtonEnable(MyEntry, MyNumber))
-        MyButton.place(x=10, y=90)
+        self.header = tk.Label(text="I have a number in mind...")
+        self.header.grid(column=0, row=0, sticky=tk.W)
 
-        self.pack(fill=BOTH,expand=True)
+        self.question = tk.Label(self, text="What's your guess?")
+        self.question.grid(column=0, row=1, sticky=tk.W)
 
+        self.input = tk.Entry(self)
+        self.input.grid(column=1, row=1, sticky=tk.W)
 
-    def ButtonEnable(self, MyEntry, MyNumber):
-        if self.IsCorrect(MyEntry.get()):
-            number = int(MyEntry.get())
-            if number != MyNumber:
-                self.GameOver(number, MyNumber)
-            else:
-                self.Win()
+        self.button = tk.Button(self, text="check", command=self.clicked)
+        self.button.grid(column=0, row=2, sticky=tk.W)
+
+        self.output = tk.Label(self, text="...")
+        self.output.grid(column=1, row=2, sticky=tk.W)
+    
+    def _is_entry_digit(self):
+        number = self.input.get()
+        if number.isdigit():
+            number = int(number)
+            return number
+
+    def clicked(self):
+        number = self._is_entry_digit()
+        if not number:
+            msg = "numbers please..."
         else:
-            self.MyLabel.config(text="I need numbers!")
-
-    def GameOver(self, number, MyNumber):
-        if number > MyNumber:
-            self.MyLabel.config(text="My number is smaller")
-        else:
-            self.MyLabel.config(text="My number is bigger")
-
-    def Win(self):
-        self.MyLabel.config(text="You WIN!")
-
-    def IsCorrect(self, MyEntry):
-        x = str(MyEntry)
-        if x.isdigit() == True:
-            return True
-        else:
-            return False
+            if number < self.number:
+                msg = "my number is bigger"
+            elif number > self.number:
+                msg = "my number is smaller"
+            elif number == self.number:
+                msg = "bingo!"
+        self.output.config(text=msg)
 
 
 if __name__ == "__main__":
-    root = Tk()
-    root.title("Guess the number")
-    root.geometry("500x300")
-    win = MainWindow()
-    root.mainloop()
-
-
+    app = Application()
+    app.mainloop()
 ```
+</details>
 
 ## MVC design pattern
 
@@ -290,215 +332,152 @@ A simple console only MVC.
 We'll add the GUI view in a bit.
 
 ```python
-from tkinter import *
+import tkinter as tk
+
 
 class ConsoleView(object):
     """A view for console."""
 
-    def select_task(self):
-        """Asks which index to look up."""
-        idx = input("which task do you want to see? ")
-        return idx
-
-    def show(self, task):
-        """Displays the task to the console. This method is called from the
-        controller."""
-        print("your task: {}".format(task))
-
-    def error(self, msg):
-        """Prints error messages coming from the controller."""
-        print("error: {}".format(msg))
-
-class Model(object):
-    """The model houses add data and should implement all methods related to
-    adding, modifying and deleting tasks."""
-
-    db = ["go to the shops", "dryhop beer", "drop of motorbike"]
-
-    def get_task(self, idx):
-        """Performs a task lookun into the database and returns it when found.
-        If no task is found, it returns an error message that will be displayed
-        in the view (via the controller)."""
-        try:
-            task = Model.db[idx]
-        except IndexError:
-            task = "task with {} not found!".format(idx)
-        return task
-
-
-class Controller(object):
-    """Binds the model and the view together."""
-
-    def __init__(self, view):
-        self.model = Model()
-        self.view = view 
-
-    def run(self):
-        """The controller's main function. Depending on what type of view is 
-        selected, a different event loop is setup. Do note that the ConsoleView
-        is not a real event loop, just a basic flow of action."""
-        if self.view is ConsoleView:
-            self.view = self.view()
-            self._run_console_view()
-        elif self.view is TkinterView:
-            root = Tk()
-            root.title("Task Manager")
-            root.geometry("500x300")
-            self.view = self.view()
-            self.view._set_controller(self)
-            root.mainloop()
-
-    def get_task_from_model(self, idx):
-        """Needed for the TkinterView to communicate with the controller."""
-        task = self.model.get_task(idx)
-        self.view.show_task(task)
-
-    def _run_console_view(self):
-        """Super simple event loop."""
-        while True:
-            try:
-                idx = self.view.select_task()
-                idx = int(idx)
-            except Exception as e:
-                self.view.error(e)
-                continue
-            task = self.model.get_task(idx)
-            self.view.show(task)
-
-
-if __name__ == "__main__":
-    view = ConsoleView
-    app = Controller(view)
-    app.run()
-```
-
-And now with the implemented `TkinterView` class.
-
-```python
-from tkinter import *
-
-class ConsoleView(object):
-    """A view for console."""
-
-    def select_task(self):
-        """Asks which index to look up."""
-        idx = input("which task do you want to see? ")
-        return idx
-
-    def show(self, task):
-        """Displays the task to the console. This method is called from the
-        controller."""
-        print("your task: {}".format(task))
-
-    def error(self, msg):
-        """Prints error messages coming from the controller."""
-        print("error: {}".format(msg))
-
-
-class TkinterView(Frame):
-    """A view using a wx.Dialog window"""
-
-    def __init__(self):
-        Frame.__init__(self, master=None)
-        #Panel
-        self.panel = PanedWindow(self, bg="green")
-        self.panel.pack(fill=BOTH, expand=True)
-
-        #Task Label
-        self.task = Label(self.panel, text="your task")
-        self.task.pack(expand=True)
-
-        #SpinBox
-        self.idx = Spinbox(self.panel, from_=0, to=2, wrap=True )
-        self.idx.pack(side= TOP)
-
-        #Button
-        self.button = Button(self.panel, text="submit", command=lambda : self.select_task())
-        self.button.pack(ipadx=60, ipady=30)
-
-        self.pack(fill=BOTH, expand=True)
-
-    def _set_controller(self, controller):
-        """Set the controller so the view can communicate it's requests to it
-        and update it's values too."""
+    def __init__(self, controller):
         self.controller = controller
 
     def select_task(self):
-        """Gets the index to look up in the model and submits the request to
-        the controller."""
-        idx = self.idx.get()
-        self.controller.get_task_from_model(idx)
+        """Asks which index to look up."""
+        idx = input("which task do you want to see? ")
+        return idx
 
-    def show_task(self, task):
-        """Updates the visual label in the view with the task. This method is
-        called from the controller."""
-        self.task.config(text=task)
+    def show_message(self, msg):
+        print("MSG: {}".format(msg))
+
+    def show(self, task):
+        """Displays the task to the console. This method is called from the
+        controller."""
+        print("your task: {}".format(task))
+
+    def error(self, msg):
+        """Prints error messages coming from the controller."""
+        print("error: {}".format(msg))
+
+    def mainloop(self):
+        """Super simple event loop."""
+        while True:
+            self.controller.request_number_of_tasks_from_model()
+            try:
+                idx = self.select_task()
+                idx = int(idx)
+            except Exception as e:
+                self.error(e)
+                continue
+            self.controller.request_task_from_model(idx)
 
 
 class Model(object):
     """The model houses add data and should implement all methods related to
     adding, modifying and deleting tasks."""
 
-    db = ["go to the shops", "dryhop beer", "drop of motorbike"]
+    def __init__(self):
+        self.db = ["go to the shops", "dryhop beer", "drop of motorbike"]
+
+    def __len__(self):
+        return len(self.db)
 
     def get_task(self, idx):
         """Performs a task lookun into the database and returns it when found.
         If no task is found, it returns an error message that will be displayed
         in the view (via the controller)."""
         try:
-            task = Model.db[int(idx)]
+            task = self.db[idx]
         except IndexError:
-            task = "task with {} not found!".format(idx)
+            task = None
         return task
 
 
 class Controller(object):
     """Binds the model and the view together."""
 
-    def __init__(self, view):
-        self.model = Model()
+    def __init__(self, model):
+        self.model = model
+
+    def set_view(self, view):
         self.view = view
+        if isinstance(view, TkinterView):
+            self.request_number_of_tasks_from_model()
 
-    def run(self):
-        """The controller's main function. Depending on what type of view is
-        selected, a different event loop is setup. Do note that the ConsoleView
-        is not a real event loop, just a basic flow of action."""
-        if self.view is ConsoleView:
-            self.view = self.view()
-            self._run_console_view()
-        elif self.view is TkinterView:
-            root = Tk()
-            root.title("Task Manager")
-            root.geometry("500x300")
-            self.view = self.view()
-            self.view._set_controller(self)
-            root.mainloop()
+    def request_number_of_tasks_from_model(self):
+        number = len(self.model)
+        self.view.show_message("you have {} tasks".format(number))
 
-    def get_task_from_model(self, idx):
-        """Needed for the TkinterView to communicate with the controller."""
+    def request_task_from_model(self, idx):
+        """Needed for the ConsoleView and TkinterView to communicate with the controller."""
         task = self.model.get_task(idx)
-        self.view.show_task(task)
-
-    def _run_console_view(self):
-        """Super simple event loop."""
-        while True:
-            try:
-                idx = self.view.select_task()
-                idx = int(idx)
-            except Exception as e:
-                self.view.error(e)
-                continue
-            task = self.model.get_task(idx)
+        if task is None:
+            self.view.error("task not found!")
+        else:
             self.view.show(task)
 
 
 if __name__ == "__main__":
-    view = TkinterView
-    app = Controller(view)
-    app.run()
-
+    model = Model()
+    controller = Controller(model)
+    view = ConsoleView(controller)
+    controller.set_view(view)
+    view.mainloop()
 ```
 
+Below you can see a `tkinter` class that acts as a drop in replacement for the `ConsoleView` class.
+
+```python
+class TkinterView(tk.Tk):
+    def __init__(self, controller):
+        tk.Tk.__init__(self)
+        self.controller = controller
+        self.title("hello world")
+        self.geometry("500x400")
+        self.resizable(0, 0)
+
+        self.header = tk.Label()
+        self.header.grid(column=0, row=0, sticky=tk.W)
+
+        self.question = tk.Label(self, text="Which task do you want to see?")
+        self.question.grid(column=0, row=1, sticky=tk.W)
+
+        self.input = tk.Entry(self)
+        self.input.grid(column=1, row=1, sticky=tk.W)
+
+        self.button = tk.Button(self, text="lookup", command=self.clicked)
+        self.button.grid(column=0, row=2, sticky=tk.W)
+
+        self.output = tk.Label(self, text="...")
+        self.output.grid(column=1, row=2, sticky=tk.W)
+    
+    def _is_entry_digit(self):
+        number = self.input.get()
+        if number.isdigit():
+            number = int(number)
+            return number
+
+    def clicked(self):
+        number = self._is_entry_digit()
+        if not number:
+            msg = "numbers please..."
+        else:
+            msg = self.controller.request_task_from_model(number)
+
+    def show_message(self, msg):
+        self.header.config(text=msg)
+
+    def show(self, task):
+        """Displays the task to the console. This method is called from the
+        controller."""
+        self.output.config(text=task)
+
+    def error(self, msg):
+        """Prints error messages coming from the controller."""
+        self.output.config(text=msg)
+```
+
+<!--
+
 For a GUI only login generator an implementation without MVC could look a bit like this.
 Note that the actual calculation is done inside the window itself.
 This is not a good idea because we should separate responsibilities into classes!
@@ -964,10 +943,16 @@ if __name__ == "__main__":
     app.mainloop()
 ````
 
+-->
+
 ## Coding challenge - Login generator with GUI
 
+TODO
+
 ## Coding challenge - Trivial pursuit with GUI
 
+TODO
+
 # WXpython
 
 ## wxpython helloworld