This is merely a silly program I felt like posting.
Code:
# python3

import tkinter

# import tkinter.messagebox  cannot set font in a messagebox.  tkinter is ridiculous, I ridicule it.
# tkinter.messagebox.showinfo(master=root, title='Spam', message='Egg Information')

a = 600  # half height
b = 500  # half width
r = 100  # radius

style = (tkinter.PIESLICE, tkinter.CHORD, tkinter.ARC)

def callback(event):
    global r
    r = max(r - 5, 15)
    print('clicked at', event.x, event.y)
    canvas.create_arc(event.x - r, event.y - r, event.x + r, event.y + r,
                      start = 0, extent = 120, outline = 'blue', style = style[r % 3], width = 4)
    canvas.create_line(b, a, event.x, event.y, arrow = tkinter.BOTH)

root = tkinter.Tk()
root.withdraw()  # a little silly
root.title('Circles and arrows')

canvas=tkinter.Canvas(root, height = 2 * a, width = 2 * b)
canvas.pack()
canvas.bind("<Button>", callback)

tkinter.Label(root,  # no reason to save it.
              text = "Click within the `canvas' to choose center of another circle",
              relief = tkinter.RIDGE,
              font = ('times', 36)).pack(
                ipady = 12,
                ipadx = 36)

canvas.create_oval(b - r, a - r, b + r, a + r, fill = 'green', activefill = 'red')

root.deiconify()
root.mainloop()