If a GUI has more than one widget, a given widget can come under focus when you explicitly click on the widget. Alternatively, the focus can be shifted to other widgets in the order that the widgets were created in the program by pressing the Tab key on the keyboard.
Therefore, it is vital to create widgets in the order that we want the user to traverse through them. Otherwise, the user will have a tough time navigating between the widgets using the keyboard.
Different widgets are designed to behave differently to different keyboard strokes. Therefore, let's spend some time trying to understand the rules of traversing through widgets using the keyboard.
Have a look at the 10.02_widget_traversal.py file to understand the keyboard ...