Tkinter reference: a GUI for Python

For example, suppose that Jukebox is a new widget class that you have created. It's probably best to have new widget classes inherit from the Frame class, so to Tkinter it acts like a frame, and you can arrange other widgets such as labels, entries, and buttons inside it.

You set the new widget's class name by passing the name as the class_ attribute to the parent constructor in your new class's constructor. Here is a fragment of the code that defines the new class:

class Jukebox(Frame):
    def __init__(self, master):
        "Constructor for the Jukebox class"
        Frame.__init__ ( self, master, class_="Jukebox" )
        self.__createWidgets()
        ...