from tkinter import *

class Ex2(Frame):
    def __init__(self, master):
        super().__init__(master)

        self.canvas = Canvas(self, height=200, width=200)
        self.canvas.grid(row=0, column=0)

        self.circle = self.canvas.create_oval(0, 0, 20, 20)
        self.move()

    def move(self):
        self.canvas.move(self.circle, 1, 1)
        self.after(100, self.move)

def runEx2():
    root = Tk()
    ex = Ex2(root)
    ex.pack()
    root.mainloop()

• Every time any key is pressed, a new circle gets created.
• All circles that have been created are moved when self.move() is called.
• Documentation for the canvas widget