#
type_ = "polygon"
#
def change_style_to(event):
    global type_
    type_ = event.widget["text"]
    print("type_ is changed on: {}".format(type_))
#
def draw(event):
    global type_
    global toolsThickness
    #
    method = {
        "polygon": event.widget.create_polygon,
        "oval": event.widget.create_oval,
    }[type_]
    #
    if b1 == "down":
        global xold, yold
        if xold is not None and yold is not None:
            method(xold,
                                   yold,
                                     event.x,
                                     event.y,
                                     width = toolsThickness,
                                        outline="black")
#
but1=Button(win3,text="oval")
but1.bind("<Button-1>", change_style_to)
but1.pack()
#
but2=Button(win3,text="polygon")
but2.bind("<Button-1>", change_style_to)
but2.pack()
#
drawing_area = Canvas(win,bg="white",width=600,height=400)
drawing_area.bind("<Motion>", motion)
drawing_area.bind("<ButtonPress-1>", b1down)
drawing_area.bind("<ButtonRelease-1>", b1up)
drawing_area.pack()

 def fill(event):
    drawing_area.configure(background="black")
but1=Button(win,text="fill")
but1.bind("<Button-1>",fill)
but1.pack()