Patch #3064: Port new turtle module and demos to 3.0.

Demo/turtle/about_turtle.txt

+
+========================================================
+    A new turtle module for Python
+========================================================
+
+Turtle graphics is a popular way for introducing programming to
+kids. It was part of the original Logo programming language developed
+by Wally Feurzig and Seymour Papert in 1966.
+
+Imagine a robotic turtle starting at (0, 0) in the x-y plane. Give it
+the command turtle.forward(15), and it moves (on-screen!) 15 pixels in
+the direction it is facing, drawing a line as it moves. Give it the
+command turtle.left(25), and it rotates in-place 25 degrees clockwise.
+
+By combining together these and similar commands, intricate shapes and
+pictures can easily be drawn.
+
+----- turtle.py
+
+This module is an extended reimplementation of turtle.py from the
+Python standard distribution up to Python 2.5. (See: http:\\www.python.org)
+
+It tries to keep the merits of turtle.py and to be (nearly) 100%
+compatible with it. This means in the first place to enable the
+learning programmer to use all the commands, classes and methods
+interactively when using the module from within IDLE run with
+the -n switch.
+
+Roughly it has the following features added:
+
+- Better animation of the turtle movements, especially of turning the
+    turtle. So the turtles can more easily be used as a visual feedback
+    instrument by the (beginning) programmer.
+
+- Different turtle shapes, gif-images as turtle shapes, user defined
+    and user controllable turtle shapes, among them compound
+    (multicolored) shapes. Turtle shapes can be stgretched and tilted, which
+    makes turtles zu very versatile geometrical objects.
+
+- Fine control over turtle movement and screen updates via delay(),
+    and enhanced tracer() and speed() methods.
+
+- Aliases for the most commonly used commands, like fd for forward etc.,
+    following the early Logo traditions. This reduces the boring work of
+    typing long sequences of commands, which often occur in a natural way
+    when kids try to program fancy pictures on their first encounter with
+    turtle graphcis.
+
+- Turtles now have an undo()-method with configurable undo-buffer.
+
+- Some simple commands/methods for creating event driven programs
+    (mouse-, key-, timer-events). Especially useful for programming games.
+
+- A scrollable Canvas class. The default scrollable Canvas can be
+    extended interactively as needed while playing around with the turtle(s).
+
+- A TurtleScreen class with methods controlling background color or
+    background image, window and canvas size and other properties of the
+    TurtleScreen.
+
+- There is a method, setworldcoordinates(), to install a user defined
+    coordinate-system for the TurtleScreen.
+
+- The implementation uses a 2-vector class named Vec2D, derived from tuple.
+    This class is public, so it can be imported by the application programmer,
+    which makes certain types of computations very natural and compact.
+
+- Appearance of the TurtleScreen and the Turtles at startup/import can be
+    configured by means of a turtle.cfg configuration file.
+    The default configuration mimics the appearance of the old turtle module.
+
+- If configured appropriately the module reads in docstrings from a docstring
+    dictionary in some different language, supplied separately  and replaces
+    the english ones by those read in. There is a utility function
+    write_docstringdict() to write a dictionary with the original (english)
+    docstrings to disc, so it can serve as a template for translations.

Demo/turtle/about_turtledemo.txt

+
+    --------------------------------------
+        About turtleDemo.py
+    --------------------------------------
+
+    Tiny demo Viewer to view turtle graphics example scripts.
+
+    Quickly and dirtyly assembled by Gregor Lingl.
+    June, 2006
+
+    For more information see: turtleDemo - Help
+
+    Have fun!

Demo/turtle/demohelp.txt

+
+
+  ----------------------------------------------
+
+      turtleDemo - Help
+
+  ----------------------------------------------
+
+  This document has two sections:
+
+  (1) How to use the demo viewer
+  (2) How to add your own demos to the demo repository
+
+
+  (1) How to use the demo viewer.
+
+  Select a demoscript from the example menu.
+  The (syntax coloured) source code appears in the left
+  source code window. IT CANNOT BE EDITED, but ONLY VIEWED!
+
+  - Press START button to start the demo.
+  - Stop execution by pressing the STOP button.
+  - Clear screen by pressing the CLEAR button.
+  - Restart by pressing the START button again.
+
+  SPECIAL demos are those which run EVENTDRIVEN.
+  (For example clock.py - or oldTurtleDemo.py which
+  in the end expects a mouse click.):
+
+      Press START button to start the demo.
+
+      - Until the EVENTLOOP is entered everything works
+      as in an ordinary demo script.
+
+      - When the EVENTLOOP is entered, you control the
+      application by using the mouse and/or keys (or it's
+      controlled by some timer events)
+      To stop it you can and must press the STOP button.
+
+      While the EVENTLOOP is running, the examples menu is disabled.
+
+      - Only after having pressed the STOP button, you may
+      restart it or choose another example script.
+
+   * * * * * * * *
+   In some rare situations there may occur interferences/conflicts
+   between events concerning the demo script and those concerning the
+   demo-viewer. (They run in the same process.) Strange behaviour may be
+   the consequence and in the worst case you must close and restart the
+   viewer.
+   * * * * * * * *
+
+
+   (2) How to add your own demos to the demo repository
+
+   - scriptname: must begin with tdemo_ ,
+     so it must have the form tdemo_<your-script-name>.py
+
+   - place: same directory as turtleDemo.py or some
+     subdirectory, the name of which must also begin with
+     tdemo_.....
+
+   - requirements on source code:
+       code must contain a main() function which will
+       be executed by the viewer (see provided example scripts)
+       main() may return a string which will be displayed
+       in the Label below the source code window (when execution
+       has finished.) 
+
+       !! For programs, which are EVENT DRIVEN, main must return
+       !! the string "EVENTLOOP". This informs the viewer, that the
+       !! script is still running and must be stopped by the user!
+
+        
+  

Demo/turtle/tdemo_I_dontlike_tiltdemo.py

+#!/usr/bin/python
+"""       turtle-example-suite:
+
+     tdemo-I_dont_like_tiltdemo.py
+
+Demostrates
+  (a) use of a tilted ellipse as
+      turtle shape
+  (b) stamping that shape
+
+We can remove it, if you don't like it.
+      Without using reset() ;-)
+ ---------------------------------------
+"""
+from tkinter.turtle import *
+import time
+
+def main():
+    reset()
+    shape("circle")
+    resizemode("user")
+
+    pu(); bk(24*18/6.283); rt(90); pd()
+    tilt(45)
+
+    pu()
+
+    turtlesize(16,10,5)
+    color("red", "violet")
+    for i in range(18):
+        fd(24)
+        lt(20)
+        stamp()
+    color("red", "")
+    for i in range(18):
+        fd(24)
+        lt(20)
+        stamp()
+
+    tilt(-15)
+    turtlesize(3, 1, 4)
+    color("blue", "yellow")
+    for i in range(17):
+        fd(24)
+        lt(20)
+        if i%2 == 0:
+            stamp()
+    time.sleep(1)
+    while undobufferentries():
+        undo()
+    ht()
+    write("OK, OVER!", align="center", font=("Courier", 18, "bold"))
+    return "Done!"
+
+if __name__=="__main__":
+    msg = main()
+    print(msg)
+#    mainloop()

Demo/turtle/tdemo_bytedesign.py

+#!/usr/bin/python
+"""      turtle-example-suite:
+
+        tdemo_bytedesign.py
+
+An example adapted from the example-suite
+of PythonCard's turtle graphcis.
+
+It's based on an article in BYTE magazine
+Problem Solving with Logo: Using Turtle
+Graphics to Redraw a Design
+November 1982, p. 118 - 134
+
+-------------------------------------------
+
+Due to the statement
+
+t.delay(0)
+
+in line 152, which sets the animation delay
+to 0, this animation runs in "line per line"
+mode as fast as possible.
+"""
+
+import math
+from tkinter.turtle import Turtle, mainloop
+from time import clock
+
+# wrapper for any additional drawing routines
+# that need to know about each other
+class Designer(Turtle):
+
+    def design(self, homePos, scale):
+        self.up()
+        for i in range(5):
+            self.forward(64.65 * scale)
+            self.down()
+            self.wheel(self.position(), scale)
+            self.up()
+            self.backward(64.65 * scale)
+            self.right(72)
+        self.up()
+        self.goto(homePos)
+        self.right(36)
+        self.forward(24.5 * scale)
+        self.right(198)
+        self.down()
+        self.centerpiece(46 * scale, 143.4, scale)
+        self.getscreen().tracer(True)
+
+    def wheel(self, initpos, scale):
+        self.right(54)
+        for i in range(4):
+            self.pentpiece(initpos, scale)
+        self.down()
+        self.left(36)
+        for i in range(5):
+            self.tripiece(initpos, scale)
+        self.left(36)
+        for i in range(5):
+            self.down()
+            self.right(72)
+            self.forward(28 * scale)
+            self.up()
+            self.backward(28 * scale)
+        self.left(54)
+        self.getscreen().update()
+
+    def tripiece(self, initpos, scale):
+        oldh = self.heading()
+        self.down()
+        self.backward(2.5 * scale)
+        self.tripolyr(31.5 * scale, scale)
+        self.up()
+        self.goto(initpos)
+        self.setheading(oldh)
+        self.down()
+        self.backward(2.5 * scale)
+        self.tripolyl(31.5 * scale, scale)
+        self.up()
+        self.goto(initpos)
+        self.setheading(oldh)
+        self.left(72)
+        self.getscreen().update()
+
+    def pentpiece(self, initpos, scale):
+        oldh = self.heading()
+        self.up()
+        self.forward(29 * scale)
+        self.down()
+        for i in range(5):
+            self.forward(18 * scale)
+            self.right(72)
+        self.pentr(18 * scale, 75, scale)
+        self.up()
+        self.goto(initpos)
+        self.setheading(oldh)
+        self.forward(29 * scale)
+        self.down()
+        for i in range(5):
+            self.forward(18 * scale)
+            self.right(72)
+        self.pentl(18 * scale, 75, scale)
+        self.up()
+        self.goto(initpos)
+        self.setheading(oldh)
+        self.left(72)
+        self.getscreen().update()
+
+    def pentl(self, side, ang, scale):
+        if side < (2 * scale): return
+        self.forward(side)
+        self.left(ang)
+        self.pentl(side - (.38 * scale), ang, scale)
+
+    def pentr(self, side, ang, scale):
+        if side < (2 * scale): return
+        self.forward(side)
+        self.right(ang)
+        self.pentr(side - (.38 * scale), ang, scale)
+
+    def tripolyr(self, side, scale):
+        if side < (4 * scale): return
+        self.forward(side)
+        self.right(111)
+        self.forward(side / 1.78)
+        self.right(111)
+        self.forward(side / 1.3)
+        self.right(146)
+        self.tripolyr(side * .75, scale)
+
+    def tripolyl(self, side, scale):
+        if side < (4 * scale): return
+        self.forward(side)
+        self.left(111)
+        self.forward(side / 1.78)
+        self.left(111)
+        self.forward(side / 1.3)
+        self.left(146)
+        self.tripolyl(side * .75, scale)
+
+    def centerpiece(self, s, a, scale):
+        self.forward(s); self.left(a)
+        if s < (7.5 * scale):
+            return
+        self.centerpiece(s - (1.2 * scale), a, scale)
+
+def main():
+    t = Designer()
+    t.speed(0)
+    t.hideturtle()
+    t.getscreen().delay(0)
+    t.getscreen().tracer(0)
+    at = clock()
+    t.design(t.position(), 2)
+    et = clock()
+    return "runtime: %.2f sec." % (et-at)
+
+if __name__ == '__main__':
+    msg = main()
+    print(msg)
+    mainloop()

Demo/turtle/tdemo_chaos.py

+# Datei: chaosplotter.py
+# Autor: Gregor Lingl
+# Datum: 31. 5. 2008
+
+# Ein einfaches Programm zur Demonstration von "chaotischem Verhalten".
+
+from tkinter.turtle import *
+
+def f(x):
+    return 3.9*x*(1-x)
+
+def g(x):
+    return 3.9*(x-x**2)
+
+def h(x):
+    return 3.9*x-3.9*x*x
+
+def coosys():
+    penup()
+    goto(-1,0)
+    pendown()
+    goto(n+1,0)
+    penup()
+    goto(0, -0.1)
+    pendown()
+    goto(-0.1, 1.1)
+
+def plot(fun, start, farbe):
+    x = start
+    pencolor(farbe)
+    penup()
+    goto(0, x)
+    pendown()
+    dot(5)
+    for i in range(n):
+        x=fun(x)
+        goto(i+1,x)
+        dot(5)
+
+def main():
+    global n
+    n = 80
+    ox=-250.0
+    oy=-150.0
+    ex= -2.0*ox / n
+    ey=300.0
+
+    reset()
+    setworldcoordinates(-1.0,-0.1, n+1, 1.1)
+    speed(0)
+    hideturtle()
+    coosys()
+    plot(f, 0.35, "blue")
+    plot(g, 0.35, "green")
+    plot(h, 0.35, "red")
+    for s in range(100):
+        setworldcoordinates(0.5*s,-0.1, n+1, 1.1)
+
+    return "Done!"
+
+if __name__ == "__main__":
+    main()
+    mainloop()

Demo/turtle/tdemo_clock.py

+#!/usr/bin/python
+# -*- coding: cp1252 -*-
+"""       turtle-example-suite:
+
+             tdemo_clock.py
+
+Enhanced clock-program, showing date
+and time
+  ------------------------------------
+   Press STOP to exit the program!
+  ------------------------------------
+"""
+from tkinter.turtle import *
+from datetime import datetime
+
+mode("logo")
+
+def jump(distanz, winkel=0):
+    penup()
+    right(winkel)
+    forward(distanz)
+    left(winkel)
+    pendown()
+
+def hand(laenge, spitze):
+    fd(laenge*1.15)
+    rt(90)
+    fd(spitze/2.0)
+    lt(120)
+    fd(spitze)
+    lt(120)
+    fd(spitze)
+    lt(120)
+    fd(spitze/2.0)
+
+def make_hand_shape(name, laenge, spitze):
+    reset()
+    jump(-laenge*0.15)
+    begin_poly()
+    hand(laenge, spitze)
+    end_poly()
+    hand_form = get_poly()
+    register_shape(name, hand_form)
+
+
+def clockface(radius):
+    reset()
+    pensize(7)
+    for i in range(60):
+        jump(radius)
+        if i % 5 == 0:
+            fd(25)
+            jump(-radius-25)
+        else:
+            dot(3)
+            jump(-radius)
+        rt(6)
+
+def setup():
+    global second_hand, minute_hand, hour_hand, writer
+    mode("logo")
+    make_hand_shape("second_hand", 125, 25)
+    make_hand_shape("minute_hand",  130, 25)
+    make_hand_shape("hour_hand", 90, 25)
+    clockface(160)
+    second_hand = Turtle()
+    second_hand.shape("second_hand")
+    second_hand.color("gray20", "gray80")
+    minute_hand = Turtle()
+    minute_hand.shape("minute_hand")
+    minute_hand.color("blue1", "red1")
+    hour_hand = Turtle()
+    hour_hand.shape("hour_hand")
+    hour_hand.color("blue3", "red3")
+    for hand in second_hand, minute_hand, hour_hand:
+        hand.resizemode("user")
+        hand.shapesize(1, 1, 3)
+        hand.speed(0)
+    ht()
+    writer = Turtle()
+    #writer.mode("logo")
+    writer.ht()
+    writer.pu()
+    writer.bk(85)
+
+
+def wochentag(t):
+    wochentag = ["Monday", "Tuesday", "Wednesday",
+        "Thursday", "Friday", "Saturday", "Sunday"]
+    return wochentag[t.weekday()]
+
+def datum(z):
+    monat = ["Jan.", "Feb.", "Mar.", "Apr.", "May", "June",
+             "July", "Aug.", "Sep.", "Oct.", "Nov.", "Dec."]
+    j = z.year
+    m = monat[z.month - 1]
+    t = z.day
+    return "%s %d %d" % (m, t, j)
+
+def tick():
+    t = datetime.today()
+    sekunde = t.second + t.microsecond*0.000001
+    minute = t.minute + sekunde/60.0
+    stunde = t.hour + minute/60.0
+    tracer(False)
+    writer.clear()
+    writer.home()
+    writer.forward(65)
+    writer.write(wochentag(t),
+                 align="center", font=("Courier", 14, "bold"))
+    writer.back(150)
+    writer.write(datum(t),
+                 align="center", font=("Courier", 14, "bold"))
+    writer.forward(85)
+    tracer(True)
+    second_hand.setheading(6*sekunde)
+    minute_hand.setheading(6*minute)
+    hour_hand.setheading(30*stunde)
+    tracer(True)
+    ontimer(tick, 100)
+
+def main():
+    tracer(False)
+    setup()
+    tracer(True)
+    tick()
+    return "EVENTLOOP"
+
+if __name__ == "__main__":
+    msg = main()
+    print(msg)
+    mainloop()

Demo/turtle/tdemo_colormixer.py

+# colormixer
+
+from tkinter.turtle import Screen, Turtle, mainloop
+import sys
+sys.setrecursionlimit(20000)   # overcomes, for now, an instability of Python 3.0
+
+class ColorTurtle(Turtle):
+
+    def __init__(self, x, y):
+        Turtle.__init__(self)
+        self.shape("turtle")
+        self.resizemode("user")
+        self.shapesize(3,3,5)
+        self.pensize(10)
+        self._color = [0,0,0]
+        self.x = x
+        self._color[x] = y
+        self.color(self._color)
+        self.speed(0)
+        self.left(90)
+        self.pu()
+        self.goto(x,0)
+        self.pd()
+        self.sety(1)
+        self.pu()
+        self.sety(y)
+        self.pencolor("gray25")
+        self.ondrag(self.shift)
+
+    def shift(self, x, y):
+        self.sety(max(0,min(y,1)))
+        self._color[self.x] = self.ycor()
+        self.fillcolor(self._color)
+        setbgcolor()
+
+def setbgcolor():
+    screen.bgcolor(red.ycor(), green.ycor(), blue.ycor())
+
+def main():
+    global screen, red, green, blue
+    screen = Screen()
+    screen.delay(0)
+    screen.setworldcoordinates(-1, -0.3, 3, 1.3)
+
+    red = ColorTurtle(0, .5)
+    green = ColorTurtle(1, .5)
+    blue = ColorTurtle(2, .5)
+    setbgcolor()
+
+    writer = Turtle()
+    writer.ht()
+    writer.pu()
+    writer.goto(1,1.15)
+    writer.write("DRAG!",align="center",font=("Arial",30,("bold","italic")))
+    return "EVENTLOOP"
+
+if __name__ == "__main__":
+    msg = main()
+    print(msg)
+    mainloop()

Demo/turtle/tdemo_forest.py

+#!/usr/bin/python
+"""     turtlegraphics-example-suite:
+
+             tdemo_forest.py
+
+Displays a 'forest' of 3 'breadth-first-trees'
+similar to the one from example tree.
+For further remarks see xtx_tree.py
+
+This example is a 'breadth-first'-rewrite of
+a Logo program written by Erich Neuwirth. See:
+http://homepage.univie.ac.at/erich.neuwirth/
+"""
+from tkinter.turtle import Turtle, colormode, tracer, mainloop
+from random import randrange
+from time import clock
+
+def symRandom(n):
+    return randrange(-n,n+1)
+
+def randomize( branchlist, angledist, sizedist ):
+    return [ (angle+symRandom(angledist),
+              sizefactor*1.01**symRandom(sizedist))
+                     for angle, sizefactor in branchlist ]
+
+def randomfd( t, distance, parts, angledist ):
+    for i in range(parts):
+        t.left(symRandom(angledist))
+        t.forward( (1.0 * distance)/parts )
+
+def tree(tlist, size, level, widthfactor, branchlists, angledist=10, sizedist=5):
+    # benutzt Liste von turtles und Liste von Zweiglisten,
+    # fuer jede turtle eine!
+    if level > 0:
+        lst = []
+        brs = []
+        for t, branchlist in list(zip(tlist,branchlists)):
+            t.pensize( size * widthfactor )
+            t.pencolor( 255 - (180 - 11 * level + symRandom(15)),
+                        180 - 11 * level + symRandom(15),
+                        0 )
+            t.pendown()
+            randomfd(t, size, level, angledist )
+            yield 1
+            for angle, sizefactor in branchlist:
+                t.left(angle)
+                lst.append(t.clone())
+                brs.append(randomize(branchlist, angledist, sizedist))
+                t.right(angle)
+        for x in tree(lst, size*sizefactor, level-1, widthfactor, brs,
+                      angledist, sizedist):
+            yield None
+
+
+def start(t,x,y):
+    colormode(255)
+    t.reset()
+    t.speed(0)
+    t.hideturtle()
+    t.left(90)
+    t.penup()
+    t.setpos(x,y)
+    t.pendown()
+
+def doit1(level, pen):
+    pen.hideturtle()
+    start(pen, 20, -208)
+    t = tree( [pen], 80, level, 0.1, [[ (45,0.69), (0,0.65), (-45,0.71) ]] )
+    return t
+
+def doit2(level, pen):
+    pen.hideturtle()
+    start(pen, -135, -130)
+    t = tree( [pen], 120, level, 0.1, [[ (45,0.69), (-45,0.71) ]] )
+    return t
+
+def doit3(level, pen):
+    pen.hideturtle()
+    start(pen, 190, -90)
+    t = tree( [pen], 100, level, 0.1, [[ (45,0.7), (0,0.72), (-45,0.65) ]] )
+    return t
+
+# Hier 3 Baumgeneratoren:
+def main():
+    p = Turtle()
+    p.ht()
+    tracer(75,0)
+    u = doit1(6, Turtle(undobuffersize=1))
+    s = doit2(7, Turtle(undobuffersize=1))
+    t = doit3(5, Turtle(undobuffersize=1))
+    a = clock()
+    while True:
+        done = 0
+        for b in u,s,t:
+            try:
+                b.__next__()
+            except:
+                done += 1
+        if done == 3:
+            break
+
+    tracer(1,10)
+    b = clock()
+    return "runtime: %.2f sec." % (b-a)
+
+if __name__ == '__main__':
+    msg = main()
+    print(msg)
+    mainloop()

Demo/turtle/tdemo_fractalcurves.py

+#!/usr/bin/python
+"""      turtle-example-suite:
+
+        tdemo_fractalCurves.py
+
+This program draws two fractal-curve-designs:
+(1) A hilbert curve (in a box)
+(2) A combination of Koch-curves.
+
+The CurvesTurtle class and the fractal-curve-
+methods are taken from the PythonCard example
+scripts for turtle-graphics.
+"""
+from tkinter.turtle import *
+from time import sleep, clock
+
+class CurvesTurtle(Pen):
+    # example derived from
+    # Turtle Geometry: The Computer as a Medium for Exploring Mathematics
+    # by Harold Abelson and Andrea diSessa
+    # p. 96-98
+    def hilbert(self, size, level, parity):
+        if level == 0:
+            return
+        # rotate and draw first subcurve with opposite parity to big curve
+        self.left(parity * 90)
+        self.hilbert(size, level - 1, -parity)
+        # interface to and draw second subcurve with same parity as big curve
+        self.forward(size)
+        self.right(parity * 90)
+        self.hilbert(size, level - 1, parity)
+        # third subcurve
+        self.forward(size)
+        self.hilbert(size, level - 1, parity)
+        # fourth subcurve
+        self.right(parity * 90)
+        self.forward(size)
+        self.hilbert(size, level - 1, -parity)
+        # a final turn is needed to make the turtle
+        # end up facing outward from the large square
+        self.left(parity * 90)
+
+    # Visual Modeling with Logo: A Structural Approach to Seeing
+    # by James Clayson
+    # Koch curve, after Helge von Koch who introduced this geometric figure in 1904
+    # p. 146
+    def fractalgon(self, n, rad, lev, dir):
+        import math
+
+        # if dir = 1 turn outward
+        # if dir = -1 turn inward
+        edge = 2 * rad * math.sin(math.pi / n)
+        self.pu()
+        self.fd(rad)
+        self.pd()
+        self.rt(180 - (90 * (n - 2) / n))
+        for i in range(n):
+            self.fractal(edge, lev, dir)
+            self.rt(360 / n)
+        self.lt(180 - (90 * (n - 2) / n))
+        self.pu()
+        self.bk(rad)
+        self.pd()
+
+    # p. 146
+    def fractal(self, dist, depth, dir):
+        if depth < 1:
+            self.fd(dist)
+            return
+        self.fractal(dist / 3, depth - 1, dir)
+        self.lt(60 * dir)
+        self.fractal(dist / 3, depth - 1, dir)
+        self.rt(120 * dir)
+        self.fractal(dist / 3, depth - 1, dir)
+        self.lt(60 * dir)
+        self.fractal(dist / 3, depth - 1, dir)
+
+def main():
+    ft = CurvesTurtle()
+
+    ft.reset()
+    ft.speed(0)
+    ft.ht()
+    ft.getscreen().tracer(1,0)
+    ft.pu()
+
+    size = 6
+    ft.setpos(-33*size, -32*size)
+    ft.pd()
+
+    ta=clock()
+    ft.fillcolor("red")
+    ft.begin_fill()
+    ft.fd(size)
+
+    ft.hilbert(size, 6, 1)
+
+    # frame
+    ft.fd(size)
+    for i in range(3):
+        ft.lt(90)
+        ft.fd(size*(64+i%2))
+    ft.pu()
+    for i in range(2):
+        ft.fd(size)
+        ft.rt(90)
+    ft.pd()
+    for i in range(4):
+        ft.fd(size*(66+i%2))
+        ft.rt(90)
+    ft.end_fill()
+    tb=clock()
+    res =  "Hilbert: %.2fsec. " % (tb-ta)
+
+    sleep(3)
+
+    ft.reset()
+    ft.speed(0)
+    ft.ht()
+    ft.getscreen().tracer(1,0)
+
+    ta=clock()
+    ft.color("black", "blue")
+    ft.begin_fill()
+    ft.fractalgon(3, 250, 4, 1)
+    ft.end_fill()
+    ft.begin_fill()
+    ft.color("red")
+    ft.fractalgon(3, 200, 4, -1)
+    ft.end_fill()
+    tb=clock()
+    res +=  "Koch: %.2fsec." % (tb-ta)
+    return res
+
+if __name__  == '__main__':
+    msg = main()
+    print(msg)
+    mainloop()

Demo/turtle/tdemo_lindenmayer_indian.py

+#!/usr/bin/python
+"""       turtle-example-suite:
+
+        xtx_lindenmayer_indian.py
+
+Each morning women in Tamil Nadu, in southern
+India, place designs, created by using rice
+flour and known as kolam on the thresholds of
+their homes.
+
+These can be described by Lindenmayer systems,
+which can easily be implemented with turtle
+graphics and Python.
+
+Two examples are shown here:
+(1) the snake kolam
+(2) anklets of Krishna
+
+Taken from Marcia Ascher: Mathematics
+Elsewhere, An Exploration of Ideas Across
+Cultures
+
+"""
+################################
+# Mini Lindenmayer tool
+###############################
+
+from tkinter.turtle import *
+
+def replace( seq, replacementRules, n ):
+    for i in range(n):
+        newseq = ""
+        for element in seq:
+            newseq = newseq + replacementRules.get(element,element)
+        seq = newseq
+    return seq
+
+def draw( commands, rules ):
+    for b in commands:
+        try:
+            rules[b]()
+        except TypeError:
+            try:
+                draw(rules[b], rules)
+            except:
+                pass
+
+
+def main():
+    ################################
+    # Example 1: Snake kolam
+    ################################
+
+
+    def r():
+        right(45)
+
+    def l():
+        left(45)
+
+    def f():
+        forward(7.5)
+
+    snake_rules = {"-":r, "+":l, "f":f, "b":"f+f+f--f--f+f+f"}
+    snake_replacementRules = {"b": "b+f+b--f--b+f+b"}
+    snake_start = "b--f--b--f"
+
+    drawing = replace(snake_start, snake_replacementRules, 3)
+
+    reset()
+    speed(3)
+    tracer(1,0)
+    ht()
+    up()
+    backward(195)
+    down()
+    draw(drawing, snake_rules)
+
+    from time import sleep
+    sleep(3)
+
+    ################################
+    # Example 2: Anklets of Krishna
+    ################################
+
+    def A():
+        color("red")
+        circle(10,90)
+
+    def B():
+        from math import sqrt
+        color("black")
+        l = 5/sqrt(2)
+        forward(l)
+        circle(l, 270)
+        forward(l)
+
+    def F():
+        color("green")
+        forward(10)
+
+    krishna_rules = {"a":A, "b":B, "f":F}
+    krishna_replacementRules = {"a" : "afbfa", "b" : "afbfbfbfa" }
+    krishna_start = "fbfbfbfb"
+
+    reset()
+    speed(0)
+    tracer(3,0)
+    ht()
+    left(45)
+    drawing = replace(krishna_start, krishna_replacementRules, 3)
+    draw(drawing, krishna_rules)
+    tracer(1)
+    return "Done!"
+
+if __name__=='__main__':
+    msg = main()
+    print(msg)
+    mainloop()

Demo/turtle/tdemo_minimal_hanoi.py

+#!/usr/bin/python
+"""       turtle-example-suite:
+
+         tdemo_minimal_hanoi.py
+
+A minimal 'Towers of Hanoi' animation:
+A tower of 6 discs is transferred from the
+left to the right peg.
+
+An imho quite elegant and concise
+implementation using a tower class, which
+is derived from the built-in type list.
+
+Discs are turtles with shape "square", but
+stretched to rectangles by shapesize()
+ ---------------------------------------
+       To exit press STOP button
+ ---------------------------------------
+"""
+from tkinter.turtle import *
+
+class Disc(Turtle):
+    def __init__(self, n):
+        Turtle.__init__(self, shape="square", visible=False)
+        self.pu()
+        self.shapesize(1.5, n*1.5, 2) # square-->rectangle
+        self.fillcolor(n/6., 0, 1-n/6.)
+        self.st()
+
+class Tower(list):
+    "Hanoi tower, a subclass of built-in type list"
+    def __init__(self, x):
+        "create an empty tower. x is x-position of peg"
+        self.x = x
+    def push(self, d):
+        d.setx(self.x)
+        d.sety(-150+34*len(self))
+        self.append(d)
+    def pop(self):
+        d = list.pop(self)
+        d.sety(150)
+        return d
+
+def hanoi(n, from_, with_, to_):
+    if n > 0:
+        hanoi(n-1, from_, to_, with_)
+        to_.push(from_.pop())
+        hanoi(n-1, with_, from_, to_)
+
+def play():
+    onkey(None,"space")
+    clear()
+    hanoi(6, t1, t2, t3)
+    write("press STOP button to exit",
+          align="center", font=("Courier", 16, "bold"))
+
+def main():
+    global t1, t2, t3
+    ht(); penup(); goto(0, -225)   # writer turtle
+    t1 = Tower(-250)
+    t2 = Tower(0)
+    t3 = Tower(250)
+    # make tower of 6 discs
+    for i in range(6,0,-1):
+        t1.push(Disc(i))
+    # prepare spartanic user interface ;-)
+    write("press spacebar to start game",
+          align="center", font=("Courier", 16, "bold"))
+    onkey(play, "space")
+    listen()
+    return "EVENTLOOP"
+
+if __name__=="__main__":
+    msg = main()
+    print(msg)
+    mainloop()

Demo/turtle/tdemo_paint.py

+#!/usr/bin/python
+"""       turtle-example-suite:
+
+            tdemo_paint.py
+
+A simple  eventdriven paint program
+
+- use left mouse button to move turtle
+- middle mouse button to change color
+- right mouse button do turn filling on/off
+ -------------------------------------------
+ Play around by clicking into the canvas
+ using all three mouse buttons.
+ -------------------------------------------
+          To exit press STOP button
+ -------------------------------------------
+"""
+from tkinter.turtle import *
+
+def switchupdown(x=0, y=0):
+    if pen()["pendown"]:
+        end_fill()
+        up()
+    else:
+        down()
+        begin_fill()
+
+def changecolor(x=0, y=0):
+    global colors
+    colors = colors[1:]+colors[:1]
+    color(colors[0])
+
+def main():
+    global colors
+    shape("circle")
+    resizemode("user")
+    shapesize(.5)
+    width(3)
+    colors=["red", "green", "blue", "yellow"]
+    color(colors[0])
+    switchupdown()
+    onscreenclick(goto,1)
+    onscreenclick(changecolor,2)
+    onscreenclick(switchupdown,3)
+    return "EVENTLOOP"
+
+if __name__ == "__main__":
+    msg = main()
+    print(msg)
+    mainloop()

Demo/turtle/tdemo_peace.py

+#!/usr/bin/python
+"""       turtle-example-suite:
+
+              tdemo_peace.py
+
+A very simple drawing suitable as a beginner's
+programming example.
+
+Uses only commands, which are also available in
+old turtle.py.
+
+Intentionally no variables are used except for the
+colorloop:
+"""
+
+from tkinter.turtle import *
+
+def main():
+    peacecolors = ("red3",  "orange", "yellow",
+                   "seagreen4", "orchid4",
+                   "royalblue1", "dodgerblue4")
+
+    reset()
+    s = Screen()
+    up()
+    goto(-320,-195)
+    width(70)
+
+    for pcolor in peacecolors:
+        color(pcolor)
+        down()
+        forward(640)
+        up()
+        backward(640)
+        left(90)
+        forward(66)
+        right(90)
+
+    width(25)
+    color("white")
+    goto(0,-170)
+    down()
+
+    circle(170)
+    left(90)
+    forward(340)
+    up()
+    left(180)
+    forward(170)
+    right(45)
+    down()
+    forward(170)
+    up()
+    backward(170)
+    left(90)
+    down()
+    forward(170)
+    up()
+
+    goto(0,300) # vanish if hideturtle() is not available ;-)
+    return "Done!!"
+
+if __name__ == "__main__":
+    main()
+    mainloop()

Demo/turtle/tdemo_penrose.py

+#!/usr/bin/python
+"""       xturtle-example-suite:
+
+          xtx_kites_and_darts.py
+
+Constructs two aperiodic penrose-tilings,
+consisting of kites and darts, by the method
+of inflation in six steps.
+
+Starting points are the patterns "sun"
+consisting of five kites and "star"
+consisting of five darts.
+
+For more information see:
+ http://en.wikipedia.org/wiki/Penrose_tiling
+ -------------------------------------------
+"""
+from tkinter.turtle import *
+from math import cos, pi
+from time import clock, sleep
+
+f = (5**0.5-1)/2.0   # (sqrt(5)-1)/2 -- golden ratio
+d = 2 * cos(3*pi/10)
+
+def kite(l):
+    fl = f * l
+    lt(36)
+    fd(l)
+    rt(108)
+    fd(fl)
+    rt(36)
+    fd(fl)
+    rt(108)
+    fd(l)
+    rt(144)
+
+def dart(l):
+    fl = f * l
+    lt(36)
+    fd(l)
+    rt(144)
+    fd(fl)
+    lt(36)
+    fd(fl)
+    rt(144)
+    fd(l)
+    rt(144)
+
+def inflatekite(l, n):
+    if n == 0:
+        px, py = pos()
+        h, x, y = int(heading()), round(px,3), round(py,3)
+        tiledict[(h,x,y)] = True
+        return
+    fl = f * l
+    lt(36)
+    inflatedart(fl, n-1)
+    fd(l)
+    rt(144)
+    inflatekite(fl, n-1)
+    lt(18)
+    fd(l*d)
+    rt(162)
+    inflatekite(fl, n-1)
+    lt(36)
+    fd(l)
+    rt(180)
+    inflatedart(fl, n-1)
+    lt(36)
+
+def inflatedart(l, n):
+    if n == 0:
+        px, py = pos()
+        h, x, y = int(heading()), round(px,3), round(py,3)
+        tiledict[(h,x,y)] = False
+        return
+    fl = f * l
+    inflatekite(fl, n-1)
+    lt(36)
+    fd(l)
+    rt(180)
+    inflatedart(fl, n-1)
+    lt(54)
+    fd(l*d)
+    rt(126)
+    inflatedart(fl, n-1)
+    fd(l)
+    rt(144)
+
+def draw(l, n, th=2):
+    clear()
+    l = l * f**n
+    shapesize(l/100.0, l/100.0, th)
+    for k in tiledict:
+        h, x, y = k
+        setpos(x, y)
+        setheading(h)
+        if tiledict[k]:
+            shape("kite")
+            color("black", (0, 0.75, 0))
+        else:
+            shape("dart")
+            color("black", (0.75, 0, 0))
+        stamp()
+
+def sun(l, n):
+    for i in range(5):
+        inflatekite(l, n)
+        lt(72)
+
+def star(l,n):
+    for i in range(5):
+        inflatedart(l, n)
+        lt(72)
+
+def makeshapes():
+    tracer(0)
+    begin_poly()
+    kite(100)
+    end_poly()
+    register_shape("kite", get_poly())
+    begin_poly()
+    dart(100)
+    end_poly()
+    register_shape("dart", get_poly())
+    tracer(1)
+
+def start():
+    reset()
+    ht()
+    pu()
+    makeshapes()
+    resizemode("user")
+
+def test(l=200, n=4, fun=sun, startpos=(0,0), th=2):
+    global tiledict
+    goto(startpos)
+    setheading(0)
+    tiledict = {}
+    a = clock()
+    tracer(0)
+    fun(l, n)
+    b = clock()
+    draw(l, n, th)
+    tracer(1)
+    c = clock()
+    print("Calculation:   %7.4f s" % (b - a))
+    print("Drawing:  %7.4f s" % (c - b))
+    print("Together: %7.4f s" % (c - a))
+    nk = len([x for x in tiledict if tiledict[x]])
+    nd = len([x for x in tiledict if not tiledict[x]])
+    print("%d kites and %d darts = %d pieces." % (nk, nd, nk+nd))
+
+def demo(fun=sun):
+    start()
+    for i in range(8):
+        a = clock()
+        test(300, i, fun)
+        b = clock()
+        t = b - a
+        if t < 2:
+            sleep(2 - t)
+
+def main():
+    #title("Penrose-tiling with kites and darts.")
+    mode("logo")
+    bgcolor(0.3, 0.3, 0)
+    demo(sun)
+    sleep(2)
+    demo(star)
+    pencolor("black")
+    goto(0,-200)
+    pencolor(0.7,0.7,1)
+    write("Please wait...",
+          align="center", font=('Arial Black', 36, 'bold'))
+    test(600, 8, startpos=(70, 117))
+    return "Done"
+
+if __name__ == "__main__":
+    msg = main()
+    mainloop()

Demo/turtle/tdemo_planet_and_moon.py

+#!/usr/bin/python
+"""       turtle-example-suite:
+
+        tdemo_planets_and_moon.py
+
+Gravitational system simulation using the
+approximation method from Feynman-lectures,
+p.9-8, using turtlegraphics.
+
+Example: heavy central body, light planet,
+very light moon!
+Planet has a circular orbit, moon a stable
+orbit around the planet.
+
+You can hold the movement temporarily by pressing
+the left mouse button with mouse over the
+scrollbar of the canvas.
+
+"""
+from tkinter.turtle import Shape, Turtle, mainloop, Vec2D as Vec
+from time import sleep
+
+G = 8
+
+class GravSys(object):
+    def __init__(self):
+        self.planets = []
+        self.t = 0
+        self.dt = 0.01
+    def init(self):
+        for p in self.planets:
+            p.init()
+    def start(self):
+        for i in range(10000):
+            self.t += self.dt
+            for p in self.planets:
+                p.step()
+
+class Star(Turtle):
+    def __init__(self, m, x, v, gravSys, shape):
+        Turtle.__init__(self, shape=shape)
+        self.penup()
+        self.m = m
+        self.setpos(x)
+        self.v = v
+        gravSys.planets.append(self)
+        self.gravSys = gravSys
+        self.resizemode("user")
+        self.pendown()
+    def init(self):
+        dt = self.gravSys.dt
+        self.a = self.acc()
+        self.v = self.v + 0.5*dt*self.a
+    def acc(self):
+        a = Vec(0,0)
+        for planet in self.gravSys.planets:
+            if planet != self:
+                v = planet.pos()-self.pos()
+                a += (G*planet.m/abs(v)**3)*v
+        return a
+    def step(self):
+        dt = self.gravSys.dt
+        self.setpos(self.pos() + dt*self.v)
+        if self.gravSys.planets.index(self) != 0:
+            self.setheading(self.towards(self.gravSys.planets[0]))
+        self.a = self.acc()
+        self.v = self.v + dt*self.a
+
+## create compound yellow/blue turtleshape for planets
+
+def main():
+    s = Turtle()
+    s.reset()
+    s.getscreen().tracer(0,0)
+    s.ht()
+    s.pu()
+    s.fd(6)
+    s.lt(90)
+    s.begin_poly()
+    s.circle(6, 180)
+    s.end_poly()
+    m1 = s.get_poly()
+    s.begin_poly()
+    s.circle(6,180)
+    s.end_poly()
+    m2 = s.get_poly()
+
+    planetshape = Shape("compound")
+    planetshape.addcomponent(m1,"orange")
+    planetshape.addcomponent(m2,"blue")
+    s.getscreen().register_shape("planet", planetshape)
+    s.getscreen().tracer(1,0)
+
+    ## setup gravitational system
+    gs = GravSys()
+    sun = Star(1000000, Vec(0,0), Vec(0,-2.5), gs, "circle")
+    sun.color("yellow")
+    sun.shapesize(1.8)
+    sun.pu()
+    earth = Star(12500, Vec(210,0), Vec(0,195), gs, "planet")
+    earth.pencolor("green")
+    earth.shapesize(0.8)
+    moon = Star(1, Vec(220,0), Vec(0,295), gs, "planet")
+    moon.pencolor("blue")
+    moon.shapesize(0.5)
+    gs.init()
+    gs.start()
+    return "Done!"
+
+if __name__ == '__main__':
+    msg = main()
+    print(msg)
+    #mainloop()

Demo/turtle/tdemo_tree.py

+#!/usr/bin/python
+"""      turtle-example-suite:
+
+             tdemo_tree.py
+
+Displays a 'breadth-first-tree' - in contrast
+to the classical Logo tree drawing programs,
+which use a depth-first-algorithm.
+
+Uses:
+(1) a tree-generator, where the drawing is
+quasi the side-effect, whereas the generator
+always yields None.
+(2) Turtle-cloning: At each branching point the
+current pen is cloned. So in the end there
+are 1024 turtles.
+"""
+from tkinter.turtle import Turtle, mainloop
+from time import clock
+
+def tree(plist, l, a, f):
+    """ plist is list of pens
+    l is length of branch
+    a is half of the angle between 2 branches
+    f is factor by which branch is shortened
+    from level to level."""
+    if l > 3:
+        lst = []
+        for p in plist:
+            p.forward(l)
+            q = p.clone()
+            p.left(a)
+            q.right(a)
+            lst.append(p)
+            lst.append(q)
+        for x in tree(lst, l*f, a, f):
+            yield None
+
+def maketree():
+    p = Turtle()
+    p.setundobuffer(None)
+    p.hideturtle()
+    p.speed(0)
+    p.getscreen().tracer(30,0)
+    p.left(90)
+    p.penup()
+    p.forward(-210)
+    p.pendown()
+    t = tree([p], 200, 65, 0.6375)
+    for x in t:
+        pass
+    print(len(p.getscreen().turtles()))
+
+def main():
+    a=clock()
+    maketree()
+    b=clock()
+    return "done: %.2f sec." % (b-a)
+
+if __name__ == "__main__":
+    msg = main()
+    print(msg)
+    mainloop()

Demo/turtle/tdemo_wikipedia.py

+"""      turtle-example-suite:
+
+          tdemo_wikipedia3.py
+
+This example is
+inspired by the Wikipedia article on turtle
+graphics. (See example wikipedia1 for URLs)
+
+First we create (ne-1) (i.e. 35 in this
+example) copies of our first turtle p.
+Then we let them perform their steps in
+parallel.
+
+Followed by a complete undo().
+"""
+from tkinter.turtle import Screen, Turtle, mainloop
+from time import clock, sleep
+
+def mn_eck(p, ne,sz):
+    turtlelist = [p]
+    #create ne-1 additional turtles
+    for i in range(1,ne):
+        q = p.clone()
+        q.rt(360.0/ne)
+        turtlelist.append(q)
+        p = q
+    for i in range(ne):
+        c = abs(ne/2.0-i)/(ne*.7)
+        # let those ne turtles make a step
+        # in parallel:
+        for t in turtlelist:
+            t.rt(360./ne)
+            t.pencolor(1-c,0,c)
+            t.fd(sz)
+
+def main():
+    s = Screen()
+    s.bgcolor("black")
+    p=Turtle()
+    p.speed(0)
+    p.hideturtle()
+    p.pencolor("red")
+    p.pensize(3)
+
+    s.tracer(36,0)
+
+    at = clock()
+    mn_eck(p, 36, 19)
+    et = clock()
+    z1 = et-at
+
+    sleep(1)
+
+    at = clock()
+    while any([t.undobufferentries() for t in s.turtles()]):
+        for t in s.turtles():
+            t.undo()
+    et = clock()
+    return "Laufzeit: %.3f sec" % (z1+et-at)
+
+
+if __name__ == '__main__':
+    msg = main()
+    print(msg)
+    mainloop()

Demo/turtle/tdemo_yinyang.py

+#!/usr/bin/python
+"""       turtle-example-suite:
+
+            tdemo_yinyang.py
+
+Another drawing suitable as a beginner's
+programming example.
+
+The small circles are drawn by the circle
+command.
+
+"""
+
+from tkinter.turtle import *
+
+def yin(radius, color1, color2):
+    width(3)
+    color("black", color1)
+    begin_fill()
+    circle(radius/2., 180)
+    circle(radius, 180)
+    left(180)
+    circle(-radius/2., 180)
+    end_fill()
+    left(90)
+    up()
+    forward(radius*0.35)
+    right(90)
+    down()
+    color(color1, color2)
+    begin_fill()
+    circle(radius*0.15)
+    end_fill()
+    left(90)
+    up()
+    backward(radius*0.35)
+    down()
+    left(90)
+
+def main():
+    reset()
+    yin(200, "black", "white")
+    yin(200, "white", "black")
+    ht()
+    return "Done!"
+
+if __name__ == '__main__':
+    main()
+    mainloop()

Demo/turtle/turtle.cfg

+width = 800
+height = 600
+canvwidth = 1200
+canvheight = 900
+shape = arrow
+mode = standard
+resizemode = auto
+fillcolor = ""
+title = Python turtle graphics demo.
+

Demo/turtle/turtleDemo.py

+#!/usr/bin/python
+import sys
+import os
+
+from tkinter import *
+from idlelib.Percolator import Percolator
+from idlelib.ColorDelegator import ColorDelegator
+from idlelib.textView import view_file # TextViewer
+from imp import reload
+
+from tkinter import turtle
+import time
+
+STARTUP = 1
+READY = 2
+RUNNING = 3
+DONE = 4
+EVENTDRIVEN = 5
+
+menufont = ("Arial", 12, NORMAL)
+btnfont = ("Arial", 12, 'bold')
+txtfont = ('Lucida Console', 8, 'normal')
+
+def getExampleEntries():
+    cwd = os.getcwd()
+    #print(cwd, os.listdir(cwd))
+    if "turtleDemo.py" not in os.listdir(cwd):
+        print("Directory of turtleDemo must be current working directory!")
+        print("But in your case this is", cwd)
+        sys.exit()
+    entries1 = [entry for entry in os.listdir(cwd) if
+                     entry.startswith("tdemo_") and
+                     not entry.endswith(".pyc")]
+    entries2 = []
+    for entry in entries1:
+        if entry.endswith(".py"):
+            entries2.append(entry)
+        else:
+            path = os.path.join(cwd,entry)
+            sys.path.append(path)
+            subdir = [entry]
+            scripts = [script for script in os.listdir(path) if
+                            script.startswith("tdemo_") and
+                            script.endswith(".py")]
+            entries2.append(subdir+scripts)
+    return entries2
+
+def showDemoHelp():
+    view_file(demo.root, "Help on turtleDemo", "demohelp.txt")
+
+def showAboutDemo():
+    view_file(demo.root, "About turtleDemo", "about_turtledemo.txt")
+
+def showAboutTurtle():
+    view_file(demo.root, "About the new turtle module.", "about_turtle.txt")
+
+class DemoWindow(object):
+
+    def __init__(self, filename=None):   #, root=None):
+        self.root = root = turtle._root = Tk()
+        root.wm_protocol("WM_DELETE_WINDOW", self._destroy)
+
+        #################
+        self.mBar = Frame(root, relief=RAISED, borderwidth=2)
+        self.mBar.pack(fill=X)
+
+        self.ExamplesBtn = self.makeLoadDemoMenu()
+        self.OptionsBtn = self.makeHelpMenu()
+        self.mBar.tk_menuBar(self.ExamplesBtn, self.OptionsBtn) #, QuitBtn)
+
+        root.title('Python turtle-graphics examples')
+        #################
+        self.left_frame = left_frame = Frame(root)
+        self.text_frame = text_frame = Frame(left_frame)
+        self.vbar = vbar =Scrollbar(text_frame, name='vbar')
+        self.text = text = Text(text_frame,
+                                name='text', padx=5, wrap='none',
+                                width=45)
+        vbar['command'] = text.yview
+        vbar.pack(side=LEFT, fill=Y)
+        #####################
+        self.hbar = hbar =Scrollbar(text_frame, name='hbar', orient=HORIZONTAL)
+        hbar['command'] = text.xview
+        hbar.pack(side=BOTTOM, fill=X)
+        #####################
+        text['yscrollcommand'] = vbar.set
+        text.config(font=txtfont)
+        text.config(xscrollcommand=hbar.set)
+        text.pack(side=LEFT, fill=Y, expand=1)
+        #####################
+        self.output_lbl = Label(left_frame, height= 1,text=" --- ", bg = "#ddf",
+                                font = ("Arial", 16, 'normal'))
+        self.output_lbl.pack(side=BOTTOM, expand=0, fill=X)
+        #####################
+        text_frame.pack(side=LEFT, fill=BOTH, expand=0)
+        left_frame.pack(side=LEFT, fill=BOTH, expand=0)
+        self.graph_frame = g_frame = Frame(root)
+
+        turtle.Screen._root = g_frame
+        turtle.Screen._canvas = turtle.ScrolledCanvas(g_frame, 800, 600, 1000, 800)
+        #xturtle.Screen._canvas.pack(expand=1, fill="both")
+        self.screen = _s_ = turtle.Screen()
+#####
+        turtle.TurtleScreen.__init__(_s_, _s_._canvas)
+#####
+        self.scanvas = _s_._canvas
+        #xturtle.RawTurtle.canvases = [self.scanvas]
+        turtle.RawTurtle.screens = [_s_]
+
+        self.scanvas.pack(side=TOP, fill=BOTH, expand=1)
+
+        self.btn_frame = btn_frame = Frame(g_frame, height=100)
+        self.start_btn = Button(btn_frame, text=" START ", font=btnfont, fg = "white",
+                                disabledforeground = "#fed", command=self.startDemo)
+        self.start_btn.pack(side=LEFT, fill=X, expand=1)
+        self.stop_btn = Button(btn_frame, text=" STOP ",  font=btnfont, fg = "white",
+                                disabledforeground = "#fed", command = self.stopIt)
+        self.stop_btn.pack(side=LEFT, fill=X, expand=1)
+        self.clear_btn = Button(btn_frame, text=" CLEAR ",  font=btnfont, fg = "white",
+                                disabledforeground = "#fed", command = self.clearCanvas)
+        self.clear_btn.pack(side=LEFT, fill=X, expand=1)
+
+        self.btn_frame.pack(side=TOP, fill=BOTH, expand=0)
+        self.graph_frame.pack(side=TOP, fill=BOTH, expand=1)
+
+        Percolator(text).insertfilter(ColorDelegator())
+        self.dirty = False
+        self.exitflag = False
+        if filename:
+            self.loadfile(filename)
+        self.configGUI(NORMAL, DISABLED, DISABLED, DISABLED,
+                       "Choose example from menu", "black")
+        self.state = STARTUP
+
+    def _destroy(self):
+        self.root.destroy()
+        sys.exit()
+
+    def configGUI(self, menu, start, stop, clear, txt="", color="blue"):
+        self.ExamplesBtn.config(state=menu)
+
+        self.start_btn.config(state=start)
+        if start==NORMAL:
+            self.start_btn.config(bg="#d00")
+        else:
+            self.start_btn.config(bg="#fca")
+
+        self.stop_btn.config(state=stop)
+        if stop==NORMAL:
+            self.stop_btn.config(bg="#d00")
+        else:
+            self.stop_btn.config(bg="#fca")
+        self.clear_btn.config(state=clear)
+
+        self.clear_btn.config(state=clear)
+        if clear==NORMAL:
+            self.clear_btn.config(bg="#d00")
+        else:
+            self.clear_btn.config(bg="#fca")
+
+        self.output_lbl.config(text=txt, fg=color)
+
+
+    def makeLoadDemoMenu(self):
+        CmdBtn = Menubutton(self.mBar, text='Examples', underline=0, font=menufont)
+        CmdBtn.pack(side=LEFT, padx="2m")
+        CmdBtn.menu = Menu(CmdBtn)
+
+        for entry in getExampleEntries():
+            def loadexample(x):
+                def emit():
+                    self.loadfile(x)
+                return emit
+            if isinstance(entry,str):
+                CmdBtn.menu.add_command(label=entry[6:-3], underline=0, font=menufont,
+                                        command=loadexample(entry))
+            else:
+                _dir, entries = entry[0], entry[1:]
+                CmdBtn.menu.choices = Menu(CmdBtn.menu)
+                for e in entries:
+                    CmdBtn.menu.choices.add_command(label=e[6:-3], underline=0, font=menufont,
+                              command = loadexample(os.path.join(_dir,e)))
+
+                CmdBtn.menu.add_cascade(label=_dir[6:],
+                                        menu = CmdBtn.menu.choices, font=menufont )
+
+        CmdBtn['menu'] = CmdBtn.menu
+        return CmdBtn
+
+
+    def makeHelpMenu(self):
+        CmdBtn = Menubutton(self.mBar, text='Help', underline=0, font = menufont)
+        CmdBtn.pack(side=LEFT, padx='2m')
+        CmdBtn.menu = Menu(CmdBtn)
+
+        CmdBtn.menu.add_command(label='About turtle.py', font=menufont, command=showAboutTurtle)
+        CmdBtn.menu.add_command(label='turtleDemo - Help', font=menufont, command=showDemoHelp)
+        CmdBtn.menu.add_command(label='About turtleDemo', font=menufont, command=showAboutDemo)
+
+        CmdBtn['menu'] = CmdBtn.menu
+        return CmdBtn
+
+    def refreshCanvas(self):
+        if not self.dirty: return
+        self.screen.clear()
+        #self.screen.mode("standard")
+        self.dirty=False
+
+    def loadfile(self,filename):
+        self.refreshCanvas()
+        if os.path.exists(filename) and not os.path.isdir(filename):
+            # load and display file text
+            f = open(filename,'r')
+            chars = f.read()
+            f.close()
+            self.text.delete("1.0", "end")
+            self.text.insert("1.0",chars)
+            direc, fname = os.path.split(filename)
+            self.root.title(fname[6:-3]+" - a Python turtle graphics example")
+            self.module = __import__(fname[:-3])
+            reload(self.module)
+            self.configGUI(NORMAL, NORMAL, DISABLED, DISABLED,
+                           "Press start button", "red")
+            self.state = READY
+
+    def startDemo(self):
+        self.refreshCanvas()
+        self.dirty = True
+        turtle.TurtleScreen._RUNNING = True
+        self.configGUI(DISABLED, DISABLED, NORMAL, DISABLED,
+                       "demo running...", "black")
+        self.screen.clear()
+        self.screen.mode("standard")
+        self.state = RUNNING
+
+        try:
+            result = self.module.main()
+            if result == "EVENTLOOP":
+                self.state = EVENTDRIVEN
+            else:
+                self.state = DONE
+        except turtle.Terminator:
+            self.state = DONE
+            result = "stopped!"
+        if self.state == DONE:
+            self.configGUI(NORMAL, NORMAL, DISABLED, NORMAL,
+                           result)
+        elif self.state == EVENTDRIVEN:
+            self.exitflag = True
+            self.configGUI(DISABLED, DISABLED, NORMAL, DISABLED,
+                           "use mouse/keys or STOP", "red")
+
+    def clearCanvas(self):
+        self.refreshCanvas()
+        self.screen._delete("all")
+        self.scanvas.config(cursor="")
+        self.configGUI(NORMAL, NORMAL, DISABLED, DISABLED)
+
+    def stopIt(self):
+        if self.exitflag:
+            self.clearCanvas()
+            self.exitflag = False
+            self.configGUI(NORMAL, NORMAL, DISABLED, DISABLED,
+                           "STOPPED!", "red")
+            turtle.TurtleScreen._RUNNING = False
+            #print "stopIT: exitflag = True"
+        else:
+            turtle.TurtleScreen._RUNNING = False
+            #print "stopIt: exitflag = False"
+
+if __name__ == '__main__':
+    demo = DemoWindow()
+    RUN = True
+    while RUN:
+        try:
+            #print("ENTERING mainloop")
+            demo.root.mainloop()
+        except AttributeError:
+            #print("AttributeError!- WAIT A MOMENT!")
+            time.sleep(0.3)
+            print("GOING ON ..")
+            demo.ckearCanvas()
+        except TypeError:
+            demo.screen._delete("all")
+            #print("CRASH!!!- WAIT A MOMENT!")
+            time.sleep(0.3)
+            #print("GOING ON ..")
+            demo.clearCanvas()
+        except:
+            print("BYE!")
+            RUN = False

Demo/turtle/turtledemo_two_canvases.py

+#!/usr/bin/python
+## DEMONSTRATES USE OF 2 CANVASES, SO CANNOT BE RUN IN DEMOVIEWER!
+"""turtle example: Using TurtleScreen and RawTurtle
+for drawing on two distinct canvases.
+"""
+from tkinter.turtle import TurtleScreen, RawTurtle, TK
+
+root = TK.Tk()
+cv1 = TK.Canvas(root, width=300, height=200, bg="#ddffff")
+cv2 = TK.Canvas(root, width=300, height=200, bg="#ffeeee")
+cv1.pack()
+cv2.pack()
+
+s1 = TurtleScreen(cv1)
+s1.bgcolor(0.85, 0.85, 1)
+s2 = TurtleScreen(cv2)
+s2.bgcolor(1, 0.85, 0.85)
+
+p = RawTurtle(s1)
+q = RawTurtle(s2)
+
+p.color("red", (1, 0.85, 0.85))
+p.width(3)
+q.color("blue", (0.85, 0.85, 1))
+q.width(3)
+
+for t in p,q:
+    t.shape("turtle")
+    t.lt(36)
+
+q.lt(180)
+
+for t in p, q:
+    t.begin_fill()
+for i in range(5):
+    for t in p, q:
+        t.fd(50)
+        t.lt(72)
+for t in p,q:
+    t.end_fill()
+    t.lt(54)
+    t.pu()
+    t.bk(50)
+
+## Want to get some info?
+
+print(s1, s2)
+print(p, q)
+print(s1.turtles())
+print(s2.turtles())
+
+TK.mainloop()

Doc/library/tkinter.turtle.rst

-:mod:`tkinter.turtle` --- Turtle graphics for Tk
-================================================
+========================================
+:mod:`turtle` --- Turtle graphics for Tk
+========================================
+
+Introduction
+============
+
+Turtle graphics is a popular way for introducing programming to kids.  It was
+part of the original Logo programming language developed by Wally Feurzig and
+Seymour Papert in 1966.
+
+Imagine a robotic turtle starting at (0, 0) in the x-y plane.  Give it the
+command ``turtle.forward(15)``, and it moves (on-screen!) 15 pixels in the
+direction it is facing, drawing a line as it moves.  Give it the command
+``turtle.left(25)``, and it rotates in-place 25 degrees clockwise.
+
+By combining together these and similar commands, intricate shapes and pictures
+can easily be drawn.
+
+The :mod:`turtle` module is an extended reimplementation of the same-named
+module from the Python standard distribution up to version Python 2.5.
+
+It tries to keep the merits of the old turtle module and to be (nearly) 100%
+compatible with it.  This means in the first place to enable the learning
+programmer to use all the commands, classes and methods interactively when using
+the module from within IDLE run with the ``-n`` switch.
+
+The turtle module provides turtle graphics primitives, in both object-oriented
+and procedure-oriented ways.  Because it uses :mod:`Tkinter` for the underlying
+graphics, it needs a version of python installed with Tk support.
+
+The object-oriented interface uses essentially two+two classes:
+
+1. The :class:`TurtleScreen` class defines graphics windows as a playground for
+   the drawing turtles.  Its constructor needs a :class:`Tkinter.Canvas` or a
+   :class:`ScrolledCanvas` as argument.  It should be used when :mod:`turtle` is
+   used as part of some application.
+
+   Derived from :class:`TurtleScreen` is the subclass :class:`Screen`.  Screen
+   is implemented as sort of singleton, so there can exist only one instance of
+   Screen at a time.  It should be used when :mod:`turtle` is used as a
+   standalone tool for doing graphics.
+
+   All methods of TurtleScreen/Screen also exist as functions, i.e. as part of
+   the procedure-oriented interface.
+
+2. :class:`RawTurtle` (alias: :class:`RawPen`) defines Turtle objects which draw
+   on a :class:`TurtleScreen`.  Its constructor needs a Canvas, ScrolledCanvas
+   or TurtleScreen as argument, so the RawTurtle objects know where to draw.
+
+   Derived from RawTurtle is the subclass :class:`Turtle` (alias: :class:`Pen`),
+   which draws on "the" :class:`Screen` - instance which is automatically
+   created, if not already present.
+
+   All methods of RawTurtle/Turtle also exist as functions, i.e. part of the
+   procedure-oriented interface.
+
+The procedural interface provides functions which are derived from the methods
+of the classes :class:`Screen` and :class:`Turtle`.  They have the same names as
+the corresponding methods.  A screen object is automativally created whenever a
+function derived from a Screen method is called.  An (unnamed) turtle object is
+automatically created whenever any of the functions derived from a Turtle method
+is called.
+
+To use multiple turtles an a screen one has to use the object-oriented interface.
+
+.. note::
+   In the following documentation the argument list for functions is given.
+   Methods, of course, have the additional first argument *self* which is
+   omitted here.
+
+
+Overview over available Turtle and Screen methods
+=================================================
+
+Turtle methods
+--------------
+
+Turtle motion
+   Move and draw
+      | :func:`forward` | :func:`fd`
+      | :func:`backward` | :func:`bk` | :func:`back`
+      | :func:`right` | :func:`rt`
+      | :func:`left` | :func:`lt`
+      | :func:`goto` | :func:`setpos` | :func:`setposition`
+      | :func:`setx`
+      | :func:`sety`
+      | :func:`setheading` | :func:`seth`
+      | :func:`home`
+      | :func:`circle`
+      | :func:`dot`
+      | :func:`stamp`
+      | :func:`clearstamp`
+      | :func:`clearstamps`
+      | :func:`undo`
+      | :func:`speed`
+
+   Tell Turtle's state
+      | :func:`position` | :func:`pos`
+      | :func:`towards`
+      | :func:`xcor`
+      | :func:`ycor`
+      | :func:`heading`
+      | :func:`distance`
+
+   Setting and measurement
+      | :func:`degrees`
+      | :func:`radians`
+
+Pen control
+   Drawing state
+      | :func:`pendown` | :func:`pd` | :func:`down`
+      | :func:`penup` | :func:`pu` | :func:`up`
+      | :func:`pensize` | :func:`width`
+      | :func:`pen`
+      | :func:`isdown`
+
+   Color control
+      | :func:`color`
+      | :func:`pencolor`
+      | :func:`fillcolor`
+
+   Filling
+      | :func:`filling`
+      | :func:`begin_fill`
+      | :func:`end_fill`
+
+   More drawing control
+      | :func:`reset`
+      | :func:`clear`
+      | :func:`write`
+
+Turtle state
+   Visibility
+      | :func:`showturtle` | :func:`st`
+      | :func:`hideturtle` | :func:`ht`
+      | :func:`isvisible`
+
+   Appearance
+      | :func:`shape`
+      | :func:`resizemode`
+      | :func:`shapesize` | :func:`turtlesize`
+      | :func:`settiltangle`
+      | :func:`tiltangle`
+      | :func:`tilt`
+
+Using events
+   | :func:`onclick`
+   | :func:`onrelease`
+   | :func:`ondrag`
+
+Special Turtle methods
+   | :func:`begin_poly`
+   | :func:`end_poly`
+   | :func:`get_poly`
+   | :func:`clone`
+   | :func:`getturtle` | :func:`getpen`
+   | :func:`getscreen`
+   | :func:`setundobuffer`
+   | :func:`undobufferentries`
+
+
+Methods of TurtleScreen/Screen
+------------------------------
+
+Window control
+   | :func:`bgcolor`
+   | :func:`bgpic`
+   | :func:`clear` | :func:`clearscreen`
+   | :func:`reset` | :func:`resetscreen`
+   | :func:`screensize`
+   | :func:`setworldcoordinates`
+
+Animation control
+   | :func:`delay`
+   | :func:`tracer`
+   | :func:`update`
+
+Using screen events
+   | :func:`listen`
+   | :func:`onkey`
+   | :func:`onclick` | :func:`onscreenclick`
+   | :func:`ontimer`
+
+Settings and special methods
+   | :func:`mode`
+   | :func:`colormode`
+   | :func:`getcanvas`
+   | :func:`getshapes`
+   | :func:`register_shape` | :func:`addshape`
+   | :func:`turtles`
+   | :func:`window_height`
+   | :func:`window_width`
+
+Methods specific to Screen
+   | :func:`bye`
+   | :func:`exitonclick`
+   | :func:`setup`
+   | :func:`title`
+
+
+Methods of RawTurtle/Turtle and corresponding functions
+=======================================================
+
+Most of the examples in this section refer to a Turtle instance called
+``turtle``.
+
+Turtle motion
+-------------
+
+.. function:: forward(distance)
+              fd(distance)
+
+   :param distance: a number (integer or float)
+
+   Move the turtle forward by the specified *distance*, in the direction the
+   turtle is headed.
+
+   >>> turtle.position()
+   (0.00, 0.00)
+   >>> turtle.forward(25)
+   >>> turtle.position()
+   (25.00,0.00)
+   >>> turtle.forward(-75)
+   >>> turtle.position()
+   (-50.00,0.00)
+
+
+.. function:: back(distance)
+              bk(distance)
+              backward(distance)
+
+   :param distance: a number
+
+   Move the turtle backward by *distance*, opposite to the direction the
+   turtle is headed.  Do not change the turtle's heading.
+
+   >>> turtle.position()
+   (0.00, 0.00)
+   >>> turtle.backward(30)
+   >>> turtle.position()
+   (-30.00, 0.00)
+
+
+.. function:: right(angle)
+              rt(angle)
+
+   :param angle: a number (integer or float)
+
+   Turn turtle right by *angle* units.  (Units are by default degrees, but
+   can be set via the :func:`degrees` and :func:`radians` functions.)  Angle
+   orientation depends on the turtle mode, see :func:`mode`.
+
+   >>> turtle.heading()
+   22.0
+   >>> turtle.right(45)
+   >>> turtle.heading()
+   337.0
+
+
+.. function:: left(angle)
+              lt(angle)
+
+   :param angle: a number (integer or float)
+
+   Turn turtle left by *angle* units.  (Units are by default degrees, but
+   can be set via the :func:`degrees` and :func:`radians` functions.)  Angle
+   orientation depends on the turtle mode, see :func:`mode`.
+
+   >>> turtle.heading()
+   22.0
+   >>> turtle.left(45)
+   >>> turtle.heading()
+   67.0
+
+.. function:: goto(x, y=None)
+              setpos(x, y=None)
+              setposition(x, y=None)
+
+    :param x: a number or a pair/vector of numbers
+    :param y: a number or ``None``
+
+    If *y* is ``None``, *x* must be a pair of coordinates or a :class:`Vec2D`
+    (e.g. as returned by :func:`pos`).
+
+    Move turtle to an absolute position.  If the pen is down, draw line.  Do
+    not change the turtle's orientation.
+
+    >>> tp = turtle.pos()
+    >>> tp
+    (0.00, 0.00)
+    >>> turtle.setpos(60,30)
+    >>> turtle.pos()
+    (60.00,30.00)
+    >>> turtle.setpos((20,80))
+    >>> turtle.pos()
+    (20.00,80.00)
+    >>> turtle.setpos(tp)
+    >>> turtle.pos()
+    (0.00,0.00)
+
+
+.. function:: setx(x)
+
+   :param x: a number (integer or float)
+
+   Set the turtle's first coordinate to *x*, leave second coordinate
+   unchanged.
+
+   >>> turtle.position()
+   (0.00, 240.00)
+   >>> turtle.setx(10)
+   >>> turtle.position()
+   (10.00, 240.00)
+
+
+.. function:: sety(y)
+
+   :param y: a number (integer or float)
+
+   Set the turtle's first coordinate to *y*, leave second coordinate
+   unchanged.
+
+   >>> turtle.position()
+   (0.00, 40.00)
+   >>> turtle.sety(-10)
+   >>> turtle.position()
+   (0.00, -10.00)
+
+
+.. function:: setheading(to_angle)
+              seth(to_angle)
+
+   :param to_angle: a number (integer or float)
 
-.. module:: tkinter.turtle
-   :platform: Tk
-   :synopsis: An environment for turtle graphics.
-.. moduleauthor:: Guido van Rossum <guido@python.org>
+   Set the orientation of the turtle to *to_angle*.  Here are some common
+   directions in degrees:
 
+   =================== ====================
+    standard mode           logo mode
+   =================== ====================
+      0 - east                0 - north
+     90 - north              90 - east
+    180 - west              180 - south
+    270 - south             270 - west
+   =================== ====================
 
-.. sectionauthor:: Moshe Zadka <moshez@zadka.site.co.il>
+   >>> turtle.setheading(90)
+   >>> turtle.heading()
+   90
 
 
-The :mod:`tkinter.turtle` module provides turtle graphics primitives, in both an
-object-oriented and procedure-oriented ways. Because it uses :mod:`tkinter` for
-the underlying graphics, it needs a version of python installed with Tk support.
+.. function:: home()
+
+   Move turtle to the origin -- coordinates (0,0) -- and set its heading to
+   its start-orientation (which depends on the mode, see :func:`mode`).
+
+
+.. function:: circle(radius, extent=None, steps=None)
+
+   :param radius: a number
+   :param extent: a number (or ``None``)
+   :param steps: an integer (or ``None``)
+
+   Draw a circle with given *radius*.  The center is *radius* units left of
+   the turtle; *extent* -- an angle -- determines which part of the circle
+   is drawn.  If *extent* is not given, draw the entire circle.  If *extent*
+   is not a full circle, one endpoint of the arc is the current pen
+   position.  Draw the arc in counterclockwise direction if *radius* is
+   positive, otherwise in clockwise direction.  Finally the direction of the
+   turtle is changed by the amount of *extent*.
+
+   As the circle is approximated by an inscribed regular polygon, *steps*
+   determines the number of steps to use.  If not given, it will be
+   calculated automatically.  May be used to draw regular polygons.
+
+   >>> turtle.circle(50)
+   >>> turtle.circle(120, 180)  # draw a semicircle
+
+
+.. function:: dot(size=None, *color)
+
+   :param size: an integer >= 1 (if given)
+   :param color: a colorstring or a numeric color tuple
+
+   Draw a circular dot with diameter *size*, using *color*.  If *size* is
+   not given, the maximum of pensize+4 and 2*pensize is used.
+
+   >>> turtle.dot()
+   >>> turtle.fd(50); turtle.dot(20, "blue"); turtle.fd(50)
+
+
+.. function:: stamp()
+
+   Stamp a copy of the turtle shape onto the canvas at the current turtle
+   position.  Return a stamp_id for that stamp, which can be used to delete
+   it by calling ``clearstamp(stamp_id)``.
+
+   >>> turtle.color("blue")
+   >>> turtle.stamp()
+   13
+   >>> turtle.fd(50)
+
+
+.. function:: clearstamp(stampid)
+
+   :param stampid: an integer, must be return value of previous
+                   :func:`stamp` call
+
+   Delete stamp with given *stampid*.
+
+   >>> turtle.color("blue")
+   >>> astamp = turtle.stamp()
+   >>> turtle.fd(50)
+   >>> turtle.clearstamp(astamp)
+
+
+.. function:: clearstamps(n=None)
+
+   :param n: an integer (or ``None``)
+
+   Delete all or first/last *n* of turtle's stamps.  If *n* is None, delete
+   all stamps, if *n* > 0 delete first *n* stamps, else if *n* < 0 delete
+   last *n* stamps.
+
+   >>> for i in range(8):
+   ...     turtle.stamp(); turtle.fd(30)
+   >>> turtle.clearstamps(2)
+   >>> turtle.clearstamps(-2)
+   >>> turtle.clearstamps()
+
+
+.. function:: undo()
+
+   Undo (repeatedly) the last turtle action(s).  Number of available
+   undo actions is determined by the size of the undobuffer.
+
+   >>> for i in range(4):
+   ...     turtle.fd(50); turtle.lt(80)
+   ...
+   >>> for i in range(8):
+   ...     turtle.undo()
+
+
+.. function:: speed(speed=None)
+
+   :param speed: an integer in the range 0..10 or a speedstring (see below)
+
+   Set the turtle's speed to an integer value in the range 0..10.  If no
+   argument is given, return current speed.
+
+   If input is a number greater than 10 or smaller than 0.5, speed is set
+   to 0.  Speedstrings are mapped to speedvalues as follows:
+
+   * "fastest":  0
+   * "fast":  10
+   * "normal":  6
+   * "slow":  3
+   * "slowest":  1
+
+   Speeds from 1 to 10 enforce increasingly faster animation of line drawing
+   and turtle turning.
+
+   Attention: *speed* = 0 means that *no* animation takes
+   place. forward/back makes turtle jump and likewise left/right make the
+   turtle turn instantly.
+
+   >>> turtle.speed(3)
+
+
+Tell Turtle's state
+-------------------
+
+.. function:: position()
+              pos()
 
-The procedural interface uses a pen and a canvas which are automagically created
-when any of the functions are called.
+   Return the turtle's current location (x,y) (as a :class:`Vec2D` vector).
 
-The :mod:`tkinter.turtle` module defines the following functions:
+   >>> turtle.pos()
+   (0.00, 240.00)
 
 
-.. function:: degrees()
+.. function:: towards(x, y=None)
 
-   Set angle measurement units to degrees.
+   :param x: a number or a pair/vector of numbers or a turtle instance
+   :param y: a number if *x* is a number, else ``None``
+
+   Return the angle between the line from turtle position to position specified
+   by (x,y), the vector or the other turtle.  This depends on the turtle's start
+   orientation which depends on the mode - "standard"/"world" or "logo").
+
+   >>> turtle.pos()
+   (10.00, 10.00)
+   >>> turtle.towards(0,0)
+   225.0
+
+
+.. function:: xcor()
+
+   Return the turtle's x coordinate.
+
+   >>> reset()
+   >>> turtle.left(60)
+   >>> turtle.forward(100)
+   >>> print turtle.xcor()
+   50.0
+
+
+.. function:: ycor()
+
+   Return the turtle's y coordinate.
+
+   >>> reset()
+   >>> turtle.left(60)
+   >>> turtle.forward(100)
+   >>> print turtle.ycor()
+   86.6025403784
+
+
+.. function:: heading()
+
+   Return the turtle's current heading (value depends on the turtle mode, see
+   :func:`mode`).
+
+   >>> turtle.left(67)
+   >>> turtle.heading()
+   67.0
+
+
+.. function:: distance(x, y=None)
+
+   :param x: a number or a pair/vector of numbers or a turtle instance
+   :param y: a number if *x* is a number, else ``None``
+
+   Return the distance from the turtle to (x,y), the given vector, or the given
+   other turtle, in turtle step units.
+
+   >>> turtle.pos()
+   (0.00, 0.00)
+   >>> turtle.distance(30,40)
+   50.0
+   >>> joe = Turtle()
+   >>> joe.forward(77)
+   >>> turtle.distance(joe)
+   77.0
+
+
+Settings for measurement
+------------------------
+
+.. function:: degrees(fullcircle=360.0)
+
+   :param fullcircle: a number
+
+   Set angle measurement units, i.e. set number of "degrees" for a full circle.
+   Default value is 360 degrees.
+
+   >>> turtle.left(90)
+   >>> turtle.heading()
+   90
+   >>> turtle.degrees(400.0)  # angle measurement in gon
+   >>> turtle.heading()
+   100
 
 
 .. function:: radians()
 
-   Set angle measurement units to radians.
+   Set the angle measurement units to radians.  Equivalent to
+   ``degrees(2*math.pi)``.
 
+   >>> turtle.heading()
+   90
+   >>> turtle.radians()
+   >>> turtle.heading()
+   1.5707963267948966
 
-.. function:: setup(**kwargs)
 
-   Sets the size and position of the main window.  Keywords are:
+Pen control
+-----------
 
-   * ``width``: either a size in pixels or a fraction of the screen. The default is
-     50% of the screen.
+Drawing state
+~~~~~~~~~~~~~
 
-   * ``height``: either a size in pixels or a fraction of the screen. The default
-     is 50% of the screen.
+.. function:: pendown()
+              pd()
+              down()
 
-   * ``startx``: starting position in pixels from the left edge of the screen.
-     ``None`` is the default value and  centers the window horizontally on screen.
+   Pull the pen down -- drawing when moving.
 
-   * ``starty``: starting position in pixels from the top edge of the screen.
-     ``None`` is the default value and  centers the window vertically on screen.
 
-   Examples::
+.. function:: penup()
+              pu()
+              up()
 
-      # Uses default geometry: 50% x 50% of screen, centered.
-      setup()  
+   Pull the pen up -- no drawing when moving.
 
-      # Sets window to 200x200 pixels, in upper left of screen
-      setup (width=200, height=200, startx=0, starty=0)
 
-      # Sets window to 75% of screen by 50% of screen, and centers it.
-      setup(width=.75, height=0.5, startx=None, starty=None)
+.. function:: pensize(width=None)
+              width(width=None)
 
+   :param width: a positive number
 
-.. function:: title(title_str)
+   Set the line thickness to *width* or return it.  If resizemode is set to
+   "auto" and turtleshape is a polygon, that polygon is drawn with the same line
+   thickness.  If no argument is given, the current pensize is returned.
 
-   Set the window's title to *title*.
+   >>> turtle.pensize()
+   1
+   >>> turtle.pensize(10)   # from here on lines of width 10 are drawn
 
 
-.. function:: done()
+.. function:: pen(pen=None, **pendict)
 
-   Enters the Tk main loop.  The window will continue to  be displayed until the
-   user closes it or the process is killed.
+   :param pen: a dictionary with some or all of the below listed keys
+   :param pendict: one or more keyword-arguments with the below listed keys as keywords
 
+   Return or set the pen's attributes in a "pen-dictionary" with the following
+   key/value pairs:
 
-.. function:: reset()
+   * "shown": True/False
+   * "pendown": True/False
+   * "pencolor": color-string or color-tuple
+   * "fillcolor": color-string or color-tuple
+   * "pensize": positive number
+   * "speed": number in range 0..10
+   * "resizemode": "auto" or "user" or "noresize"
+   * "stretchfactor": (positive number, positive number)
+   * "outline": positive number
+   * "tilt": number
 
-   Clear the screen, re-center the pen, and set variables to the default values.
+   This dicionary can be used as argument for a subsequent call to :func:`pen`
+   to restore the former pen-state.  Moreover one or more of these attributes
+   can be provided as keyword-arguments.  This can be used to set several pen
+   attributes in one statement.
 
+   >>> turtle.pen(fillcolor="black", pencolor="red", pensize=10)
+   >>> turtle.pen()
+   {'pensize': 10, 'shown': True, 'resizemode': 'auto', 'outline': 1,
+   'pencolor': 'red', 'pendown': True, 'fillcolor': 'black',
+   'stretchfactor': (1,1), 'speed': 3}
+   >>> penstate=turtle.pen()
+   >>> turtle.color("yellow","")
+   >>> turtle.penup()
+   >>> turtle.pen()
+   {'pensize': 10, 'shown': True, 'resizemode': 'auto', 'outline': 1,
+   'pencolor': 'yellow', 'pendown': False, 'fillcolor': '',
+   'stretchfactor': (1,1), 'speed': 3}
+   >>> p.pen(penstate, fillcolor="green")
+   >>> p.pen()
+   {'pensize': 10, 'shown': True, 'resizemode': 'auto', 'outline': 1,
+   'pencolor': 'red', 'pendown': True, 'fillcolor': 'green',
+   'stretchfactor': (1,1), 'speed': 3}
 
-.. function:: clear()
 
-   Clear the screen.
+.. function:: isdown()
 
+   Return ``True`` if pen is down, ``False`` if it's up.
 
-.. function:: tracer(flag)
+   >>> turtle.penup()
+   >>> turtle.isdown()
+   False
+   >>> turtle.pendown()
+   >>> turtle.isdown()
+   True
 
-   Set tracing on/off (according to whether flag is true or not). Tracing means
-   line are drawn more slowly, with an animation of an arrow along the  line.
 
+Color control
+~~~~~~~~~~~~~
 
-.. function:: speed(speed)
+.. function:: pencolor(*args)
 
-   Set the speed of the turtle. Valid values for the parameter *speed* are
-   ``'fastest'`` (no delay), ``'fast'``, (delay 5ms), ``'normal'`` (delay 10ms),
-   ``'slow'`` (delay 15ms), and ``'slowest'`` (delay 20ms).
+   Return or set the pencolor.
 
+   Four input formats are allowed:
 
-.. function:: delay(delay)
+   ``pencolor()``
+      Return the current pencolor as color specification string, possibly in
+      hex-number format (see example).  May be used as input to another
+      color/pencolor/fillcolor call.
 
-   Set the speed of the turtle to *delay*, which is given in ms.
+   ``pencolor(colorstring)``
+      Set pencolor to *colorstring*, which is a Tk color specification string,
+      such as ``"red"``, ``"yellow"``, or ``"#33cc8c"``.
 
+   ``pencolor((r, g, b))``
+      Set pencolor to the RGB color represented by the tuple of *r*, *g*, and
+      *b*.  Each of *r*, *g*, and *b* must be in the range 0..colormode, where
+      colormode is either 1.0 or 255 (see :func:`colormode`).
 
-.. function:: forward(distance)
+   ``pencolor(r, g, b)``
+      Set pencolor to the RGB color represented by *r*, *g*, and *b*.  Each of
+      *r*, *g*, and *b* must be in the range 0..colormode.
 
-   Go forward *distance* steps.
+    If turtleshape is a polygon, the outline of that polygon is drawn with the
+    newly set pencolor.
 
+    >>> turtle.pencolor("brown")
+    >>> tup = (0.2, 0.8, 0.55)
+    >>> turtle.pencolor(tup)
+    >>> turtle.pencolor()
+    "#33cc8c"
 
-.. function:: backward(distance)
 
-   Go backward *distance* steps.
+.. function:: fillcolor(*args)
 
+   Return or set the fillcolor.
 
-.. function:: left(angle)
+   Four input formats are allowed:
 
-   Turn left *angle* units. Units are by default degrees, but can be set via the
-   :func:`degrees` and :func:`radians` functions.
+   ``fillcolor()``
+      Return the current fillcolor as color specification string, possibly in
+      hex-number format (see example).  May be used as input to another
+      color/pencolor/fillcolor call.
 
+   ``fillcolor(colorstring)``
+      Set fillcolor to *colorstring*, which is a Tk color specification string,
+      such as ``"red"``, ``"yellow"``, or ``"#33cc8c"``.
 
-.. function:: right(angle)
+   ``fillcolor((r, g, b))``
+      Set fillcolor to the RGB color represented by the tuple of *r*, *g*, and
+      *b*.  Each of *r*, *g*, and *b* must be in the range 0..colormode, where
+      colormode is either 1.0 or 255 (see :func:`colormode`).
 
-   Turn right *angle* units. Units are by default degrees, but can be set via the
-   :func:`degrees` and :func:`radians` functions.
+   ``fillcolor(r, g, b)``
+      Set fillcolor to the RGB color represented by *r*, *g*, and *b*.  Each of
+      *r*, *g*, and *b* must be in the range 0..colormode.
 
+    If turtleshape is a polygon, the interior of that polygon is drawn
+    with the newly set fillcolor.
 
-.. function:: up()
+    >>> turtle.fillcolor("violet")
+    >>> col = turtle.pencolor()
+    >>> turtle.fillcolor(col)
+    >>> turtle.fillcolor(0, .5, 0)
 
-   Move the pen up --- stop drawing.
 
+.. function:: color(*args)
 
-.. function:: down()
+   Return or set pencolor and fillcolor.
 
-   Move the pen down --- draw when moving.
+   Several input formats are allowed.  They use 0 to 3 arguments as
+   follows:
 
+   ``color()``
+      Return the current pencolor and the current fillcolor as a pair of color
+      specification strings as returned by :func:`pencolor` and
+      :func:`fillcolor`.
 
-.. function:: width(width)
+   ``color(colorstring)``, ``color((r,g,b))``, ``color(r,g,b)``
+      Inputs as in :func:`pencolor`, set both, fillcolor and pencolor, to the
+      given value.
 
-   Set the line width to *width*.
+   ``color(colorstring1, colorstring2)``, ``color((r1,g1,b1), (r2,g2,b2))``
+      Equivalent to ``pencolor(colorstring1)`` and ``fillcolor(colorstring2)``
+      and analogously if the other input format is used.
 
+    If turtleshape is a polygon, outline and interior of that polygon is drawn
+    with the newly set colors.
 
-.. function:: color(s)
-              color((r, g, b))
-              color(r, g, b)
+    >>> turtle.color("red", "green")
+    >>> turtle.color()
+    ("red", "green")
+    >>> colormode(255)
+    >>> color((40, 80, 120), (160, 200, 240))
+    >>> color()
+    ("#285078", "#a0c8f0")
 
-   Set the pen color.  In the first form, the color is specified as a Tk color
-   specification as a string.  The second form specifies the color as a tuple of
-   the RGB values, each in the range [0..1].  For the third form, the color is
-   specified giving the RGB values as three separate parameters (each in the range
-   [0..1]).
 
+See also: Screen method :func:`colormode`.
 
-.. function:: write(text[, move])
 
-   Write *text* at the current pen position. If *move* is true, the pen is moved to
-   the bottom-right corner of the text. By default, *move* is false.
+Filling
+~~~~~~~
 
+.. function:: filling()
 
-.. function:: fill(flag)
+   Return fillstate (``True`` if filling, ``False`` else).
 
-   The complete specifications are rather complex, but the recommended  usage is:
-   call ``fill(1)`` before drawing a path you want to fill, and call ``fill(0)``
-   when you finish to draw the path.
+   >>> turtle.begin_fill()
+   >>> if turtle.filling():
+   ...    turtle.pensize(5)
+   else:
+   ...    turtle.pensize(3)
 
 
 .. function:: begin_fill()
 
-   Switch turtle into filling mode;  Must eventually be followed by a corresponding
-   end_fill() call. Otherwise it will be ignored.
+   To be called just before drawing a shape to be filled.
+
+   >>> turtle.color("black", "red")
+   >>> turtle.begin_fill()
+   >>> turtle.circle(60)
+   >>> turtle.end_fill()
 
 
 .. function:: end_fill()
 
-   End filling mode, and fill the shape; equivalent to ``fill(0)``.
+   Fill the shape drawn after the last call to :func:`begin_fill`.
 
 
-.. function:: circle(radius[, extent])
+More drawing control
+~~~~~~~~~~~~~~~~~~~~
 
-   Draw a circle with radius *radius* whose center-point is *radius* units left of
-   the turtle. *extent* determines which part of a circle is drawn: if not given it
-   defaults to a full circle.
+.. function:: reset()
 
-   If *extent* is not a full circle, one endpoint of the arc is the current pen
-   position. The arc is drawn in a counter clockwise direction if *radius* is
-   positive, otherwise in a clockwise direction.  In the process, the direction of
-   the turtle is changed by the amount of the *extent*.
+   Delete the turtle's drawings from the screen, re-center the turtle and set
+   variables to the default values.
 
+   >>> turtle.position()
+   (0.00,-22.00)
+   >>> turtle.heading()
+   100.0
+   >>> turtle.reset()
+   >>> turtle.position()
+   (0.00,0.00)
+   >>> turtle.heading()
+   0.0
 
-.. function:: goto(x, y)
-              goto((x, y))
 
-   Go to co-ordinates *x*, *y*.  The co-ordinates may be specified either as two
-   separate arguments or as a 2-tuple.
+.. function:: clear()
 
+   Delete the turtle's drawings from the screen.  Do not move turtle.  State and
+   position of the turtle as well as drawings of other turtles are not affected.
 
-.. function:: towards(x, y)
 
-   Return the angle of the line from the turtle's position to the point *x*, *y*.
-   The co-ordinates may be specified either as two separate arguments, as a
-   2-tuple, or as another pen object.
+.. function:: write(arg, move=False, align="left", font=("Arial", 8, "normal"))
 
+   :param arg: object to be written to the TurtleScreen
+   :param move: True/False
+   :param align: one of the strings "left", "center" or right"
+   :param font: a triple (fontname, fontsize, fonttype)
 
-.. function:: heading()
+   Write text - the string representation of *arg* - at the current turtle
+   position according to *align* ("left", "center" or right") and with the given
+   font.  If *move* is True, the pen is moved to the bottom-right corner of the
+   text.  By default, *move* is False.
 
-   Return the current orientation of the turtle.
+   >>> turtle.write("Home = ", True, align="center")
+   >>> turtle.write((0,0), True)
 
 
-.. function:: setheading(angle)
+Turtle state
+------------
 
-   Set the orientation of the turtle to *angle*.
+Visibility
+~~~~~~~~~~
 
+.. function:: showturtle()
+              st()
 
-.. function:: position()
+   Make the turtle visible.
 
-   Return the current location of the turtle as an ``(x,y)`` pair.
+   >>> turtle.hideturtle()
+   >>> turtle.showturtle()
 
 
-.. function:: setx(x)
+.. function:: hideturtle()
+              ht()
 
-   Set the x coordinate of the turtle to *x*.
+   Make the turtle invisible.  It's a good idea to do this while you're in the
+   middle of doing some complex drawing, because hiding the turtle speeds up the
+   drawing observably.
 
+   >>> turtle.hideturtle()
 
-.. function:: sety(y)
 
-   Set the y coordinate of the turtle to *y*.
+.. function:: isvisible()
 
+   Return True if the Turtle is shown, False if it's hidden.
 
-.. function:: window_width()
+   >>> turtle.hideturtle()
+   >>> print turtle.isvisible():
+   False
+
+
+Appearance
+~~~~~~~~~~
+
+.. function:: shape(name=None)
+
+   :param name: a string which is a valid shapename
+
+   Set turtle shape to shape with given *name* or, if name is not given, return
+   name of current shape.  Shape with *name* must exist in the TurtleScreen's
+   shape dictionary.  Initially there are the following polygon shapes: "arrow",
+   "turtle", "circle", "square", "triangle", "classic".  To learn about how to
+   deal with shapes see Screen method :func:`register_shape`.
+
+   >>> turtle.shape()
+   "arrow"
+   >>> turtle.shape("turtle")
+   >>> turtle.shape()
+   "turtle"
+
+
+.. function:: resizemode(rmode=None)
+
+   :param rmode: one of the strings "auto", "user", "noresize"
+
+   Set resizemode to one of the values: "auto", "user", "noresize".  If *rmode*
+   is not given, return current resizemode.  Different resizemodes have the
+   following effects:
+
+   - "auto": adapts the appearance of the turtle corresponding to the value of pensize.
+   - "user": adapts the appearance of the turtle according to the values of
+     stretchfactor and outlinewidth (outline), which are set by
+     :func:`shapesize`.
+   - "noresize": no adaption of the turtle's appearance takes place.
+
+   resizemode("user") is called by :func:`shapesize` when used with arguments.
+
+   >>> turtle.resizemode("noresize")
+   >>> turtle.resizemode()
+   "noresize"
+
+
+.. function:: shapesize(stretch_wid=None, stretch_len=None, outline=None)
+
+   :param stretch_wid: positive number
+   :param stretch_len: positive number
+   :param outline: positive number
+
+   Return or set the pen's attributes x/y-stretchfactors and/or outline.  Set
+   resizemode to "user".  If and only if resizemode is set to "user", the turtle
+   will be displayed stretched according to its stretchfactors: *stretch_wid* is
+   stretchfactor perpendicular to its orientation, *stretch_len* is
+   stretchfactor in direction of its orientation, *outline* determines the width
+   of the shapes's outline.
+
+   >>> turtle.resizemode("user")
+   >>> turtle.shapesize(5, 5, 12)
+   >>> turtle.shapesize(outline=8)
+
+
+.. function:: tilt(angle)
+
+   :param angle: a number
+
+   Rotate the turtleshape by *angle* from its current tilt-angle, but do *not*
+   change the turtle's heading (direction of movement).
+
+   >>> turtle.shape("circle")
+   >>> turtle.shapesize(5,2)
+   >>> turtle.tilt(30)
+   >>> turtle.fd(50)
+   >>> turtle.tilt(30)
+   >>> turtle.fd(50)
+
+
+.. function:: settiltangle(angle)
+
+   :param angle: a number
+
+   Rotate the turtleshape to point in the direction specified by *angle*,
+   regardless of its current tilt-angle.  *Do not* change the turtle's heading
+   (direction of movement).
+
+   >>> turtle.shape("circle")
+   >>> turtle.shapesize(5,2)
+   >>> turtle.settiltangle(45)
+   >>> stamp()
+   >>> turtle.fd(50)
+   >>> turtle.settiltangle(-45)
+   >>> stamp()
+   >>> turtle.fd(50)
+
+
+.. function:: tiltangle()
+
+   Return the current tilt-angle, i.e. the angle between the orientation of the
+   turtleshape and the heading of the turtle (its direction of movement).
+
+   >>> turtle.shape("circle")
+   >>> turtle.shapesize(5,2)
+   >>> turtle.tilt(45)
+   >>> turtle.tiltangle()
+   45
+
+
+Using events
+------------
+
+.. function:: onclick(fun, btn=1, add=None)
+
+   :param fun: a function with two arguments which will be called with the
+               coordinates of the clicked point on the canvas
+   :param num: number of the mouse-button, defaults to 1 (left mouse button)
+   :param add: ``True`` or ``False`` -- if ``True``, a new binding will be
+               added, otherwise it will replace a former binding
+
+   Bind *fun* to mouse-click events on this turtle.  If *fun* is ``None``,
+   existing bindings are removed.  Example for the anonymous turtle, i.e. the
+   procedural way:
+
+   >>> def turn(x, y):
+   ...     left(180)
+   ...
+   >>> onclick(turn)  # Now clicking into the turtle will turn it.
+   >>> onclick(None)  # event-binding will be removed
+
+
+.. function:: onrelease(fun, btn=1, add=None)
+
+   :param fun: a function with two arguments which will be called with the
+               coordinates of the clicked point on the canvas
+   :param num: number of the mouse-button, defaults to 1 (left mouse button)
+   :param add: ``True`` or ``False`` -- if ``True``, a new binding will be
+               added, otherwise it will replace a former binding
+
+   Bind *fun* to mouse-button-release events on this turtle.  If *fun* is
+   ``None``, existing bindings are removed.
+
+   >>> class MyTurtle(Turtle):
+   ...     def glow(self,x,y):
+   ...         self.fillcolor("red")
+   ...     def unglow(self,x,y):
+   ...         self.fillcolor("")
+   ...
+   >>> turtle = MyTurtle()
+   >>> turtle.onclick(turtle.glow)     # clicking on turtle turns fillcolor red,
+   >>> turtle.onrelease(turtle.unglow) # releasing turns it to transparent.
+
+
+.. function:: ondrag(fun, btn=1, add=None)
+
+   :param fun: a function with two arguments which will be called with the
+               coordinates of the clicked point on the canvas
+   :param num: number of the mouse-button, defaults to 1 (left mouse button)
+   :param add: ``True`` or ``False`` -- if ``True``, a new binding will be
+               added, otherwise it will replace a former binding
+
+   Bind *fun* to mouse-move events on this turtle.  If *fun* is ``None``,
+   existing bindings are removed.
 
-   Return the width of the canvas window.
+   Remark: Every sequence of mouse-move-events on a turtle is preceded by a
+   mouse-click event on that turtle.
+
+   >>> turtle.ondrag(turtle.goto)
+   # Subsequently, clicking and dragging the Turtle will move it across
+   # the screen thereby producing handdrawings (if pen is down).
+
+
+Special Turtle methods
+----------------------
+
+.. function:: begin_poly()
+
+   Start recording the vertices of a polygon.  Current turtle position is first
+   vertex of polygon.
+
+
+.. function:: end_poly()
+
+   Stop recording the vertices of a polygon.  Current turtle position is last
+   vertex of polygon.  This will be connected with the first vertex.
+
+
+.. function:: get_poly()
+
+   Return the last recorded polygon.
+
+   >>> p = turtle.get_poly()
+   >>> turtle.register_shape("myFavouriteShape", p)
+
+
+.. function:: clone()
+
+   Create and return a clone of the turtle with same position, heading and
+   turtle properties.
+
+   >>> mick = Turtle()
+   >>> joe = mick.clone()
+
+
+.. function:: getturtle()
+
+   Return the Turtle object itself.  Only reasonable use: as a function to
+   return the "anonymous turtle":
+
+   >>> pet = getturtle()
+   >>> pet.fd(50)
+   >>> pet
+   <turtle.Turtle object at 0x01417350>
+   >>> turtles()
+   [<turtle.Turtle object at 0x01417350>]
+
+
+.. function:: getscreen()
+
+   Return the :class:`TurtleScreen` object the turtle is drawing on.
+   TurtleScreen methods can then be called for that object.
+
+   >>> ts = turtle.getscreen()
+   >>> ts
+   <turtle.Screen object at 0x01417710>
+   >>> ts.bgcolor("pink")
+
+
+.. function:: setundobuffer(size)
+
+   :param size: an integer or ``None``
+
+   Set or disable undobuffer.  If *size* is an integer an empty undobuffer of
+   given size is installed.  *size* gives the maximum number of turtle actions
+   that can be undone by the :func:`undo` method/function.  If *size* is
+   ``None``, the undobuffer is disabled.
+
+   >>> turtle.setundobuffer(42)
+
+
+.. function:: undobufferentries()
+
+   Return number of entries in the undobuffer.
+
+   >>> while undobufferentries():
+   ...     undo()
+
+
+.. _compoundshapes:
+
+Excursus about the use of compound shapes
+-----------------------------------------
+
+To use compound turtle shapes, which consist of several polygons of different
+color, you must use the helper class :class:`Shape` explicitly as described
+below:
+
+1. Create an empty Shape object of type "compound".
+2. Add as many components to this object as desired, using the
+   :meth:`addcomponent` method.
+
+   For example:
+
+   >>> s = Shape("compound")
+   >>> poly1 = ((0,0),(10,-5),(0,10),(-10,-5))
+   >>> s.addcomponent(poly1, "red", "blue")
+   >>> poly2 = ((0,0),(10,-5),(-10,-5))
+   >>> s.addcomponent(poly2, "blue", "red")
+
+3. Now add the Shape to the Screen's shapelist and use it:
+
+   >>> register_shape("myshape", s)
+   >>> shape("myshape")
+
+
+.. note::
+
+   The :class:`Shape` class is used internally by the :func:`register_shape`
+   method in different ways.  The application programmer has to deal with the
+   Shape class *only* when using compound shapes like shown above!
+
+
+Methods of TurtleScreen/Screen and corresponding functions
+==========================================================
+
+Most of the examples in this section refer to a TurtleScreen instance called
+``screen``.
+
+
+Window control
+--------------
+
+.. function:: bgcolor(*args)
+
+   :param args: a color string or three numbers in the range 0..colormode or a
+                3-tuple of such numbers
+
+   Set or return background color of the TurtleScreen.
+
+   >>> screen.bgcolor("orange")
+   >>> screen.bgcolor()
+   "orange"
+   >>> screen.bgcolor(0.5,0,0.5)
+   >>> screen.bgcolor()
+   "#800080"
+
+
+.. function:: bgpic(picname=None)
+
+   :param picname: a string, name of a gif-file or ``"nopic"``, or ``None``
+
+   Set background image or return name of current backgroundimage.  If *picname*
+   is a filename, set the corresponding image as background.  If *picname* is
+   ``"nopic"``, delete background image, if present.  If *picname* is ``None``,
+   return the filename of the current backgroundimage.
+
+   >>> screen.bgpic()
+   "nopic"
+   >>> screen.bgpic("landscape.gif")
+   >>> screen.bgpic()
+   "landscape.gif"
+
+
+.. function:: clear()
+              clearscreen()
+
+   Delete all drawings and all turtles from the TurtleScreen.  Reset the now
+   empty TurtleScreen to its initial state: white background, no background
+   image, no event bindings and tracing on.
+
+   .. note::
+      This TurtleScreen method is available as a global function only under the
+      name ``clearscreen``.  The global function ``clear`` is another one
+      derived from the Turtle method ``clear``.
+
+
+.. function:: reset()
+              resetscreen()
+
+   Reset all Turtles on the Screen to their initial state.
+
+   .. note::
+      This TurtleScreen method is available as a global function only under the
+      name ``resetscreen``.  The global function ``reset`` is another one
+      derived from the Turtle method ``reset``.
+
+
+.. function:: screensize(canvwidth=None, canvheight=None, bg=None)
+
+   :param canvwidth: positive integer, new width of canvas in pixels
+   :param canvheight: positive integer, new height of canvas in pixels
+   :param bg: colorstring or color-tupel, new background color
+
+   If no arguments are given, return current (canvaswidth, canvasheight).  Else
+   resize the canvas the turtles are drawing on.  Do not alter the drawing
+   window.  To observe hidden parts of the canvas, use the scrollbars. With this
+   method, one can make visible those parts of a drawing which were outside the
+   canvas before.
+
+      >>> turtle.screensize(2000,1500)
+      # e.g. to search for an erroneously escaped turtle ;-)
+
+
+.. function:: setworldcoordinates(llx, lly, urx, ury)
+
+   :param llx: a number, x-coordinate of lower left corner of canvas
+   :param lly: a number, y-coordinate of lower left corner of canvas
+   :param urx: a number, x-coordinate of upper right corner of canvas
+   :param ury: a number, y-coordinate of upper right corner of canvas
+
+   Set up user-defined coordinate system and switch to mode "world" if
+   necessary.  This performs a ``screen.reset()``.  If mode "world" is already
+   active, all drawings are redrawn according to the new coordinates.
+
+   **ATTENTION**: in user-defined coordinate systems angles may appear
+   distorted.
+
+   >>> screen.reset()
+   >>> screen.setworldcoordinates(-50,-7.5,50,7.5)
+   >>> for _ in range(72):
+   ...     left(10)
+   ...
+   >>> for _ in range(8):
+   ...     left(45); fd(2)   # a regular octogon
+
+
+Animation control
+-----------------
+
+.. function:: delay(delay=None)
+
+   :param delay: positive integer
+
+   Set or return the drawing *delay* in milliseconds.  (This is approximately
+   the time interval between two consecutived canvas updates.)  The longer the
+   drawing delay, the slower the animation.
+
+   Optional argument:
+
+   >>> screen.delay(15)
+   >>> screen.delay()
+   15
+
+
+.. function:: tracer(n=None, delay=None)
+
+   :param n: nonnegative integer
+   :param delay: nonnegative integer
+
+   Turn turtle animation on/off and set delay for update drawings.  If *n* is
+   given, only each n-th regular screen update is really performed.  (Can be
+   used to accelerate the drawing of complex graphics.)  Second argument sets
+   delay value (see :func:`delay`).
+
+   >>> screen.tracer(8, 25)
+   >>> dist = 2
+   >>> for i in range(200):
+   ...     fd(dist)
+   ...     rt(90)
+   ...     dist += 2
+
+
+.. function:: update()
+
+   Perform a TurtleScreen update. To be used when tracer is turned off.
+
+See also the RawTurtle/Turtle method :func:`speed`.
+
+
+Using screen events
+-------------------
+
+.. function:: listen(xdummy=None, ydummy=None)
+
+   Set focus on TurtleScreen (in order to collect key-events).  Dummy arguments
+   are provided in order to be able to pass :func:`listen` to the onclick method.
+
+
+.. function:: onkey(fun, key)
+
+   :param fun: a function with no arguments or ``None``
+   :param key: a string: key (e.g. "a") or key-symbol (e.g. "space")
+
+   Bind *fun* to key-release event of key.  If *fun* is ``None``, event bindings
+   are removed. Remark: in order to be able to register key-events, TurtleScreen
+   must have the focus. (See method :func:`listen`.)
+
+   >>> def f():
+   ...     fd(50)
+   ...     lt(60)
+   ...
+   >>> screen.onkey(f, "Up")
+   >>> screen.listen()
+
+
+.. function:: onclick(fun, btn=1, add=None)
+              onscreenclick(fun, btn=1, add=None)
+
+   :param fun: a function with two arguments which will be called with the
+               coordinates of the clicked point on the canvas
+   :param num: number of the mouse-button, defaults to 1 (left mouse button)
+   :param add: ``True`` or ``False`` -- if ``True``, a new binding will be
+               added, otherwise it will replace a former binding
+
+   Bind *fun* to mouse-click events on this screen.  If *fun* is ``None``,
+   existing bindings are removed.
+
+   Example for a TurtleScreen instance named ``screen`` and a Turtle instance
+   named turtle:
+
+   >>> screen.onclick(turtle.goto)
+   # Subsequently clicking into the TurtleScreen will
+   # make the turtle move to the clicked point.
+   >>> screen.onclick(None)  # remove event binding again
+
+   .. note::
+      This TurtleScreen method is available as a global function only under the
+      name ``onscreenclick``.  The global function ``onclick`` is another one
+      derived from the Turtle method ``onclick``.
+
+
+.. function:: ontimer(fun, t=0)
+
+   :param fun: a function with no arguments
+   :param t: a number >= 0
+
+   Install a timer that calls *fun* after *t* milliseconds.
+
+   >>> running = True
+   >>> def f():
+           if running:
+               fd(50)
+               lt(60)
+               screen.ontimer(f, 250)
+   >>> f()   ### makes the turtle marching around
+   >>> running = False
+
+
+Settings and special methods
+----------------------------
+
+.. function:: mode(mode=None)
+
+   :param mode: one of the strings "standard", "logo" or "world"
+
+   Set turtle mode ("standard", "logo" or "world") and perform reset.  If mode
+   is not given, current mode is returned.
+
+   Mode "standard" is compatible with old :mod:`turtle`.  Mode "logo" is
+   compatible with most Logo turtle graphics.  Mode "world" uses user-defined
+   "world coordinates". **Attention**: in this mode angles appear distorted if
+   ``x/y`` unit-ratio doesn't equal 1.
+
+   ============ ========================= ===================
+       Mode      Initial turtle heading     positive angles
+   ============ ========================= ===================
+    "standard"    to the right (east)       counterclockwise
+      "logo"        upward    (north)         clockwise
+   ============ ========================= ===================
+
+   >>> mode("logo")   # resets turtle heading to north
+   >>> mode()
+   "logo"
+
+
+.. function:: colormode(cmode=None)
+
+   :param cmode: one of the values 1.0 or 255
+
+   Return the colormode or set it to 1.0 or 255.  Subsequently *r*, *g*, *b*
+   values of color triples have to be in the range 0..\ *cmode*.
+
+   >>> screen.colormode()
+   1.0
+   >>> screen.colormode(255)
+   >>> turtle.pencolor(240,160,80)
+
+
+.. function:: getcanvas()
+
+   Return the Canvas of this TurtleScreen.  Useful for insiders who know what to
+   do with a Tkinter Canvas.
+
+   >>> cv = screen.getcanvas()
+   >>> cv
+   <turtle.ScrolledCanvas instance at 0x010742D8>
+
+
+.. function:: getshapes()
+
+   Return a list of names of all currently available turtle shapes.
+
+   >>> screen.getshapes()
+   ["arrow", "blank", "circle", ..., "turtle"]
+
+
+.. function:: register_shape(name, shape=None)
+              addshape(name, shape=None)
+
+   There are three different ways to call this function:
+
+   (1) *name* is the name of a gif-file and *shape* is ``None``: Install the
+       corresponding image shape.
+
+       .. note::
+          Image shapes *do not* rotate when turning the turtle, so they do not
+          display the heading of the turtle!
+
+   (2) *name* is an arbitrary string and *shape* is a tuple of pairs of
+       coordinates: Install the corresponding polygon shape.
+
+   (3) *name* is an arbitrary string and shape is a (compound) :class:`Shape`
+       object: Install the corresponding compound shape.
+
+   Add a turtle shape to TurtleScreen's shapelist.  Only thusly registered
+   shapes can be used by issuing the command ``shape(shapename)``.
+
+   >>> screen.register_shape("turtle.gif")
+   >>> screen.register_shape("triangle", ((5,-3), (0,5), (-5,-3)))
+
+
+.. function:: turtles()
+
+   Return the list of turtles on the screen.
+
+   >>> for turtle in screen.turtles()
+   ...     turtle.color("red")
 
 
 .. function:: window_height()
 
-   Return the height of the canvas window.
+   Return the height of the turtle window.
 
+   >>> screen.window_height()
+   480
 
-This module also does ``from math import *``, so see the documentation for the
-:mod:`math` module for additional constants and functions useful for turtle
-graphics.
 
+.. function:: window_width()
+
+   Return the width of the turtle window.
+
+   >>> screen.window_width()
+   640
+
+
+.. _screenspecific:
+
+Methods specific to Screen, not inherited from TurtleScreen
+-----------------------------------------------------------
+
+.. function:: bye()
+
+   Shut the turtlegraphics window.
+
+
+.. function:: exitonclick()
+
+   Bind bye() method to mouse clicks on the Screen.
 
-.. function:: demo()
 
-   Exercise the module a bit.
+   If the value "using_IDLE" in the configuration dictionary is ``False``
+   (default value), also enter mainloop.  Remark: If IDLE with the ``-n`` switch
+   (no subprocess) is used, this value should be set to ``True`` in
+   :file:`turtle.cfg`.  In this case IDLE's own mainloop is active also for the
+   client script.
 
 
-.. exception:: Error
+.. function:: setup(width=_CFG["width"], height=_CFG["height"], startx=_CFG["leftright"], starty=_CFG["topbottom"])
 
-   Exception raised on any error caught by this module.
+   Set the size and position of the main window.  Default values of arguments
+   are stored in the configuration dicionary and can be changed via a
+   :file:`turtle.cfg` file.
 
-For examples, see the code of the :func:`demo` function.
+   :param width: if an integer, a size in pixels, if a float, a fraction of the
+                 screen; default is 50% of screen
+   :param height: if an integer, the height in pixels, if a float, a fraction of
+                  the screen; default is 75% of screen
+   :param startx: if positive, starting position in pixels from the left
+                  edge of the screen, if negative from the right edge, if None,
+                  center window horizontally
+   :param startx: if positive, starting position in pixels from the top
+                  edge of the screen, if negative from the bottom edge, if None,
+                  center window vertically
 
-This module defines the following classes:
+   >>> screen.setup (width=200, height=200, startx=0, starty=0)
+   # sets window to 200x200 pixels, in upper left of screen
+   >>> screen.setup(width=.75, height=0.5, startx=None, starty=None)
+   # sets window to 75% of screen by 50% of screen and centers
 
 
-.. class:: Pen()
+.. function:: title(titlestring)
 
-   Define a pen. All above functions can be called as a methods on the given pen.
-   The constructor automatically creates a canvas do be drawn on.
+   :param titlestring: a string that is shown in the titlebar of the turtle
+                       graphics window
+
+   Set title of turtle window to *titlestring*.
+
+   >>> screen.title("Welcome to the turtle zoo!")
+
+
+The public classes of the module :mod:`turtle`
+==============================================
+
+
+.. class:: RawTurtle(canvas)
+           RawPen(canvas)
+
+   :param canvas: a :class:`Tkinter.Canvas`, a :class:`ScrolledCanvas` or a
+                  :class:`TurtleScreen`
+
+    Create a turtle.  The turtle has all methods described above as "methods of
+    Turtle/RawTurtle".
 
 
 .. class:: Turtle()
 
-   Define a pen. This is essentially a synonym for ``Pen()``; :class:`Turtle` is an
-   empty subclass of :class:`Pen`.
+    Subclass of RawTurtle, has the same interface but draws on a default
+    :class:`Screen` object created automatically when needed for the first time.
 
 
-.. class:: RawPen(canvas)
+.. class:: TurtleScreen(cv)
 
-   Define a pen which draws on a canvas *canvas*. This is useful if  you want to
-   use the module to create graphics in a "real" program.
+   :param cv: a :class:`Tkinter.Canvas`
 
+   Provides screen oriented methods like :func:`setbg` etc. that are described
+   above.
 
-.. _pen-rawpen-objects:
+.. class:: Screen()
 
-Turtle, Pen and RawPen Objects
-------------------------------
+   Subclass of TurtleScreen, with :ref:`four methods added <screenspecific>`.
+
+   
+.. class:: ScrolledCavas(master)
 
-Most of the global functions available in the module are also available as
-methods of the :class:`Turtle`, :class:`Pen` and :class:`RawPen` classes,
-affecting only the state of the given pen.
+   :param master: some Tkinter widget to contain the ScrolledCanvas, i.e.
+      a Tkinter-canvas with scrollbars added
 
-The only method which is more powerful as a method is :func:`degrees`, which
-takes an optional argument letting  you specify the number of units
-corresponding to a full circle:
+   Used by class Screen, which thus automatically provides a ScrolledCanvas as
+   playground for the turtles.
 
+.. class:: Shape(type_, data)
 
-.. method:: Turtle.degrees([fullcircle])
+   :param type\_: one of the strings "polygon", "image", "compound"
 
-   *fullcircle* is by default 360. This can cause the pen to have any angular units
-   whatever: give *fullcircle* ``2*pi`` for radians, or 400 for gradians.
+   Data structure modeling shapes.  The pair ``(type_, data)`` must follow this
+   specification:
+
+
+   =========== ===========
+   *type_*     *data*
+   =========== ===========
+   "polygon"   a polygon-tuple, i.e. a tuple of pairs of coordinates
+   "image"     an image  (in this form only used internally!)
+   "compound"  ``None`` (a compund shape has to be constructed using the
+               :meth:`addcomponent` method)
+   =========== ===========
+                
+   .. method:: addcomponent(poly, fill, outline=None)
+
+      :param poly: a polygon, i.e. a tuple of pairs of numbers
+      :param fill: a color the *poly* will be filled with
+      :param outline: a color for the poly's outline (if given)
+     
+      Example:
+
+      >>> poly = ((0,0),(10,-5),(0,10),(-10,-5))
+      >>> s = Shape("compound")
+      >>> s.addcomponent(poly, "red", "blue")
+      # .. add more components and then use register_shape()
+
+      See :ref:`compoundshapes`.
+
+
+.. class:: Vec2D(x, y)
+
+   A two-dimensional vector class, used as a helper class for implementing
+   turtle graphics.  May be useful for turtle graphics programs too.  Derived
+   from tuple, so a vector is a tuple!
+
+   Provides (for *a*, *b* vectors, *k* number):
+
+   * ``a + b`` vector addition
+   * ``a - b`` vector subtraction
+   * ``a * b`` inner product
+   * ``k * a`` and ``a * k`` multiplication with scalar
+   * ``abs(a)`` absolute value of a
+   * ``a.rotate(angle)`` rotation
+
+
+Help and configuration
+======================
+
+How to use help
+---------------
+
+The public methods of the Screen and Turtle classes are documented extensively
+via docstrings.  So these can be used as online-help via the Python help
+facilities:
+
+- When using IDLE, tooltips show the signatures and first lines of the
+  docstrings of typed in function-/method calls.
+
+- Calling :func:`help` on methods or functions displays the docstrings::
+
+     >>> help(Screen.bgcolor)
+     Help on method bgcolor in module turtle:
+    
+     bgcolor(self, *args) unbound turtle.Screen method
+         Set or return backgroundcolor of the TurtleScreen.
+    
+         Arguments (if given): a color string or three numbers
+         in the range 0..colormode or a 3-tuple of such numbers.
+    
+    
+           >>> screen.bgcolor("orange")
+           >>> screen.bgcolor()
+           "orange"
+           >>> screen.bgcolor(0.5,0,0.5)
+           >>> screen.bgcolor()
+           "#800080"
+    
+     >>> help(Turtle.penup)
+     Help on method penup in module turtle:
+    
+     penup(self) unbound turtle.Turtle method
+         Pull the pen up -- no drawing when moving.
+    
+         Aliases: penup | pu | up
+    
+         No argument
+    
+         >>> turtle.penup()
+
+- The docstrings of the functions which are derived from methods have a modified
+  form::
+
+     >>> help(bgcolor)
+     Help on function bgcolor in module turtle:
+    
+     bgcolor(*args)
+         Set or return backgroundcolor of the TurtleScreen.
+    
+         Arguments (if given): a color string or three numbers
+         in the range 0..colormode or a 3-tuple of such numbers.
+    
+         Example::
+    
+           >>> bgcolor("orange")
+           >>> bgcolor()
+           "orange"
+           >>> bgcolor(0.5,0,0.5)
+           >>> bgcolor()
+           "#800080"
+    
+     >>> help(penup)
+     Help on function penup in module turtle:
+    
+     penup()
+         Pull the pen up -- no drawing when moving.
+    
+         Aliases: penup | pu | up
+    
+         No argument
+    
+         Example:
+         >>> penup()
+
+These modified docstrings are created automatically together with the function
+definitions that are derived from the methods at import time.
+
+
+Translation of docstrings into different languages
+--------------------------------------------------
+
+There is a utility to create a dictionary the keys of which are the method names
+and the values of which are the docstrings of the public methods of the classes
+Screen and Turtle.
+
+.. function:: write_docstringdict(filename="turtle_docstringdict")
+
+   :param filename: a string, used as filename
+
+   Create and write docstring-dictionary to a Python script with the given
+   filename.  This function has to be called explicitly (it is not used by the
+   turtle graphics classes).  The docstring dictionary will be written to the
+   Python script :file:`{filename}.py`.  It is intended to serve as a template
+   for translation of the docstrings into different languages.
+
+If you (or your students) want to use :mod:`turtle` with online help in your
+native language, you have to translate the docstrings and save the resulting
+file as e.g. :file:`turtle_docstringdict_german.py`.
+
+If you have an appropriate entry in your :file:`turtle.cfg` file this dictionary
+will be read in at import time and will replace the original English docstrings.
+
+At the time of this writing there are docstring dictionaries in German and in
+Italian.  (Requests please to glingl@aon.at.)
+
+
+
+How to configure Screen and Turtles
+-----------------------------------
+
+The built-in default configuration mimics the appearance and behaviour of the
+old turtle module in order to retain best possible compatibility with it.
+
+If you want to use a different configuration which better reflects the features
+of this module or which better fits to your needs, e.g. for use in a classroom,
+you can prepare a configuration file ``turtle.cfg`` which will be read at import
+time and modify the configuration according to its settings.
+
+The built in configuration would correspond to the following turtle.cfg::
+
+   width = 0.5
+   height = 0.75
+   leftright = None
+   topbottom = None
+   canvwidth = 400
+   canvheight = 300
+   mode = standard
+   colormode = 1.0
+   delay = 10
+   undobuffersize = 1000
+   shape = classic
+   pencolor = black
+   fillcolor = black
+   resizemode = noresize
+   visible = True
+   language = english
+   exampleturtle = turtle
+   examplescreen = screen
+   title = Python Turtle Graphics
+   using_IDLE = False
+
+Short explanation of selected entries:
+
+- The first four lines correspond to the arguments of the :meth:`Screen.setup`
+  method.
+- Line 5 and 6 correspond to the arguments of the method
+  :meth:`Screen.screensize`.
+- *shape* can be any of the built-in shapes, e.g: arrow, turtle, etc.  For more
+  info try ``help(shape)``.
+- If you want to use no fillcolor (i.e. make the turtle transparent), you have
+  to write ``fillcolor = ""`` (but all nonempty strings must not have quotes in
+  the cfg-file).
+- If you want to reflect the turtle its state, you have to use ``resizemode =
+  auto``.
+- If you set e.g. ``language = italian`` the docstringdict
+  :file:`turtle_docstringdict_italian.py` will be loaded at import time (if
+  present on the import path, e.g. in the same directory as :mod:`turtle`.
+- The entries *exampleturtle* and *examplescreen* define the names of these
+  objects as they occur in the docstrings.  The transformation of
+  method-docstrings to function-docstrings will delete these names from the
+  docstrings.
+- *using_IDLE*: Set this to ``True`` if you regularly work with IDLE and its -n
+  switch ("no subprocess").  This will prevent :func:`exitonclick` to enter the
+  mainloop.
+
+There can be a :file:`turtle.cfg` file in the directory where :mod:`turtle` is
+stored and an additional one in the current working directory.  The latter will
+override the settings of the first one.
+
+The :file:`Demo/turtle` directory contains a :file:`turtle.cfg` file.  You can
+study it as an example and see its effects when running the demos (preferably
+not from within the demo-viewer).
+
+
+Demo scripts
+============
+
+There is a set of demo scripts in the turtledemo directory located in the
+:file:`Demo/turtle` directory in the source distribution.
+
+It contains:
+
+- a set of 15 demo scripts demonstrating differet features of the new module
+  :mod:`turtle`
+- a demo viewer :file:`turtleDemo.py` which can be used to view the sourcecode
+  of the scripts and run them at the same time. 14 of the examples can be
+  accessed via the Examples menu; all of them can also be run standalone.
+- The example :file:`turtledemo_two_canvases.py` demonstrates the simultaneous
+  use of two canvases with the turtle module.  Therefore it only can be run
+  standalone.
+- There is a :file:`turtle.cfg` file in this directory, which also serves as an
+  example for how to write and use such files.
+
+The demoscripts are:
+
++----------------+------------------------------+-----------------------+
+| Name           | Description                  | Features              |
++----------------+------------------------------+-----------------------+
+| bytedesign     | complex classical            | :func:`tracer`, delay,|
+|                | turtlegraphics pattern       | :func:`update`        |
++----------------+------------------------------+-----------------------+
+| chaos          | graphs verhust dynamics,     | world coordinates     |
+|                | proves that you must not     |                       |
+|                | trust computers' computations|                       |
++----------------+------------------------------+-----------------------+
+| clock          | analog clock showing time    | turtles as clock's    |
+|                | of your computer             | hands, ontimer        |
++----------------+------------------------------+-----------------------+
+| colormixer     | experiment with r, g, b      | :func:`ondrag`        |
++----------------+------------------------------+-----------------------+
+| fractalcurves  | Hilbert & Koch curves        | recursion             |
++----------------+------------------------------+-----------------------+
+| lindenmayer    | ethnomathematics             | L-System              |
+|                | (indian kolams)              |                       |
++----------------+------------------------------+-----------------------+
+| minimal_hanoi  | Towers of Hanoi              | Rectangular Turtles   |
+|                |                              | as Hanoi discs        |
+|                |                              | (shape, shapesize)    |
++----------------+------------------------------+-----------------------+
+| paint          | super minimalistic           | :func:`onclick`       |
+|                | drawing program              |                       |
++----------------+------------------------------+-----------------------+
+| peace          | elementary                   | turtle: appearance    |
+|                |                              | and animation         |
++----------------+------------------------------+-----------------------+
+| penrose        | aperiodic tiling with        | :func:`stamp`         |
+|                | kites and darts              |                       |
++----------------+------------------------------+-----------------------+
+| planet_and_moon| simulation of                | compound shapes,      |
+|                | gravitational system         | :class:`Vec2D`        |
++----------------+------------------------------+-----------------------+
+| tree           | a (graphical) breadth        | :func:`clone`         |
+|                | first tree (using generators)|                       |
++----------------+------------------------------+-----------------------+
+| wikipedia      | a pattern from the wikipedia | :func:`clone`,        |
+|                | article on turtle graphics   | :func:`undo`          |
++----------------+------------------------------+-----------------------+
+| yingyang       | another elementary example   | :func:`circle`        |
++----------------+------------------------------+-----------------------+
+
+Have fun!
+
+
+Changes since Python 2.6
+========================
+
+- The methods :meth:`Turtle.tracer`, :meth:`Turtle.window_width` and 
+  :meth:`Turtle.window_height` have been eliminated. 
+  Methods with these names and functionality are now available only 
+  as methods of :class:`Screen`. The functions derived from these remain
+  available. (In fact already in Python 2.6 these methods were merely 
+  duplications of the corresponding 
+  :class:`TurtleScreen`/:class:`Screen`-methods.)
+
+- The method :meth:`Turtle.fill` has been eliminated. 
+  The behaviour of :meth:`begin_fill` and :meth:`end_fill` 
+  have changed slightly: now  every filling-process must be completed with an 
+  ``end_fill()`` call.
+  
+- A method :meth:`Turtle.filling` has been added. It returns a boolean
+  value: ``True`` if a filling process is under way, ``False`` otherwise.
+  This behaviour corresponds to a ``fill()`` call without arguments in
+  Python 2.6
 

Misc/ACKS

@@ -411,6 +411,7 @@ Christopher Lindblad
 Bjorn Lindqvist
 Per Lindqvist
 Eric Lindvall
+Gregor Lingl
 Nick Lockwood
 Stephanie Lockwood
 Anne Lord