from Tkinter import *

class RubberBandCanvas(Canvas):
    def __init__(self, master=None, **kwargs):
        Canvas.__init__(self, master, **kwargs)
        self.bind("<Button-1>", self.on_button_press)
        self.bind("<B1-Motion>", self.on_move_press)
        self.bind("<ButtonRelease-1>", self.on_button_release)
        self.line = None
        self.points = []

    def on_button_press(self, event):
        self.points.append((event.x, event.y))

    def on_move_press(self, event):
        self.delete(self.line)
        self.line = self.create_line(self.points + [(event.x, event.y)])

    def on_button_release(self, event):
        self.delete(self.line)
        self.create_line(self.points + [(event.x, event.y)], fill="blue")

class Application(Frame):
    def create_widgets(self):
        self.canvas = RubberBandCanvas(self)
        self.canvas.pack(fill=BOTH, expand=YES)

    def __init__(self, master=None):
        Frame.__init__(self, master)
        self.pack()
        self.create_widgets()

app = Application()
app.master.title("Rubber Band Canvas")
app.mainloop()