from Tkinter import *

# this file demonstrates the movement of a single canvas item under mouse control

class Test(Frame):

    ###################################################################

    ###### Event callbacks for THE CANVAS (not the stuff drawn on it)

    ###################################################################

    def mouseDown(self, event):

        # remember where the mouse went down

        self.lastx = event.x

        self.lasty = event.y

    def mouseMove(self, event):

        # whatever the mouse is over gets tagged as CURRENT for free by tk.

        self.draw.move(CURRENT, event.x - self.lastx, event.y - self.lasty)

        self.lastx = event.x

        self.lasty = event.y

    ###################################################################

    ###### Event callbacks for canvas ITEMS (stuff drawn on the canvas)

    ###################################################################

    def mouseEnter(self, event):

        # the CURRENT tag is applied to the object the cursor is over.

        # this happens automatically.

        self.draw.itemconfig(CURRENT, fill="red")

    def mouseLeave(self, event):

        # the CURRENT tag is applied to the object the cursor is over.

        # this happens automatically.

        self.draw.itemconfig(CURRENT, fill="blue")

    def createWidgets(self):

        self.QUIT = Button(self, text='QUIT', foreground='red',

                           command=self.quit)

        self.QUIT.pack(side=LEFT, fill=BOTH)

        self.draw = Canvas(self, width="5i", height="5i")

        self.draw.pack(side=LEFT)

        fred = self.draw.create_oval(0, 0, 20, 20,

                                     fill="green", tags="selected")

        self.draw.tag_bind(fred, "<Any-Enter>", self.mouseEnter)

        self.draw.tag_bind(fred, "<Any-Leave>", self.mouseLeave)

        Widget.bind(self.draw, "<1>", self.mouseDown)

        Widget.bind(self.draw, "<B1-Motion>", self.mouseMove)

    def __init__(self, master=None):

        Frame.__init__(self, master)

        Pack.config(self)

        self.createWidgets()

test = Test()

test.mainloop()