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

22 files changed, 2020 insertions, 0 deletions

diff --git a/Demo/turtle/about_turtle.txt b/Demo/turtle/about_turtle.txt
new file mode 100644
index 0000000..e4ba217
--- /dev/null
+++ b/Demo/turtle/about_turtle.txt
@@ -0,0 +1,76 @@
+
+========================================================
+    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.
diff --git a/Demo/turtle/about_turtledemo.txt b/Demo/turtle/about_turtledemo.txt
new file mode 100644
index 0000000..54c25a5
--- /dev/null
+++ b/Demo/turtle/about_turtledemo.txt
@@ -0,0 +1,13 @@
+
+    --------------------------------------
+        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!
diff --git a/Demo/turtle/demohelp.txt b/Demo/turtle/demohelp.txt
new file mode 100644
index 0000000..5683875
--- /dev/null
+++ b/Demo/turtle/demohelp.txt
@@ -0,0 +1,75 @@
+
+
+  ----------------------------------------------
+
+      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!
+
+        
+  
diff --git a/Demo/turtle/tdemo_I_dontlike_tiltdemo.py b/Demo/turtle/tdemo_I_dontlike_tiltdemo.py
new file mode 100644
index 0000000..7cae675
--- /dev/null
+++ b/Demo/turtle/tdemo_I_dontlike_tiltdemo.py
@@ -0,0 +1,58 @@
+#!/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()
diff --git a/Demo/turtle/tdemo_bytedesign.py b/Demo/turtle/tdemo_bytedesign.py
new file mode 100644
index 0000000..742df06
--- /dev/null
+++ b/Demo/turtle/tdemo_bytedesign.py
@@ -0,0 +1,162 @@
+#!/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()
diff --git a/Demo/turtle/tdemo_chaos.py b/Demo/turtle/tdemo_chaos.py
new file mode 100644
index 0000000..73a0453
--- /dev/null
+++ b/Demo/turtle/tdemo_chaos.py
@@ -0,0 +1,63 @@
+# 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()
diff --git a/Demo/turtle/tdemo_clock.py b/Demo/turtle/tdemo_clock.py
new file mode 100644
index 0000000..c91d4c5
--- /dev/null
+++ b/Demo/turtle/tdemo_clock.py
@@ -0,0 +1,132 @@
+#!/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()
diff --git a/Demo/turtle/tdemo_colormixer.py b/Demo/turtle/tdemo_colormixer.py
new file mode 100644
index 0000000..93179b3
--- /dev/null
+++ b/Demo/turtle/tdemo_colormixer.py
@@ -0,0 +1,60 @@
+# 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()
diff --git a/Demo/turtle/tdemo_forest.py b/Demo/turtle/tdemo_forest.py
new file mode 100644
index 0000000..b117e3b
--- /dev/null
+++ b/Demo/turtle/tdemo_forest.py
@@ -0,0 +1,109 @@
+#!/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()
diff --git a/Demo/turtle/tdemo_fractalcurves.py b/Demo/turtle/tdemo_fractalcurves.py
new file mode 100644
index 0000000..b7c387b
--- /dev/null
+++ b/Demo/turtle/tdemo_fractalcurves.py
@@ -0,0 +1,138 @@
+#!/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()
diff --git a/Demo/turtle/tdemo_lindenmayer_indian.py b/Demo/turtle/tdemo_lindenmayer_indian.py
new file mode 100644
index 0000000..07dd936
--- /dev/null
+++ b/Demo/turtle/tdemo_lindenmayer_indian.py
@@ -0,0 +1,119 @@
+#!/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()
diff --git a/Demo/turtle/tdemo_minimal_hanoi.py b/Demo/turtle/tdemo_minimal_hanoi.py
new file mode 100644
index 0000000..97e937f
--- /dev/null
+++ b/Demo/turtle/tdemo_minimal_hanoi.py
@@ -0,0 +1,76 @@
+#!/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()
diff --git a/Demo/turtle/tdemo_paint.py b/Demo/turtle/tdemo_paint.py
new file mode 100644
index 0000000..97c8756
--- /dev/null
+++ b/Demo/turtle/tdemo_paint.py
@@ -0,0 +1,50 @@
+#!/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()
diff --git a/Demo/turtle/tdemo_peace.py b/Demo/turtle/tdemo_peace.py
new file mode 100644
index 0000000..7f7db14
--- /dev/null
+++ b/Demo/turtle/tdemo_peace.py
@@ -0,0 +1,65 @@
+#!/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()
diff --git a/Demo/turtle/tdemo_penrose.py b/Demo/turtle/tdemo_penrose.py
new file mode 100644
index 0000000..e99a5f5
--- /dev/null
+++ b/Demo/turtle/tdemo_penrose.py
@@ -0,0 +1,181 @@
+#!/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()
diff --git a/Demo/turtle/tdemo_planet_and_moon.py b/Demo/turtle/tdemo_planet_and_moon.py
new file mode 100644
index 0000000..855b56f
--- /dev/null
+++ b/Demo/turtle/tdemo_planet_and_moon.py
@@ -0,0 +1,113 @@
+#!/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()
diff --git a/Demo/turtle/tdemo_tree.py b/Demo/turtle/tdemo_tree.py
new file mode 100644
index 0000000..3e7f34f
--- /dev/null
+++ b/Demo/turtle/tdemo_tree.py
@@ -0,0 +1,63 @@
+#!/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()
diff --git a/Demo/turtle/tdemo_wikipedia.py b/Demo/turtle/tdemo_wikipedia.py
new file mode 100644
index 0000000..f694312
--- /dev/null
+++ b/Demo/turtle/tdemo_wikipedia.py
@@ -0,0 +1,65 @@
+"""      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()
diff --git a/Demo/turtle/tdemo_yinyang.py b/Demo/turtle/tdemo_yinyang.py
new file mode 100644
index 0000000..a47dd71
--- /dev/null
+++ b/Demo/turtle/tdemo_yinyang.py
@@ -0,0 +1,49 @@
+#!/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()
diff --git a/Demo/turtle/turtle.cfg b/Demo/turtle/turtle.cfg
new file mode 100644
index 0000000..bd89a74
--- /dev/null
+++ b/Demo/turtle/turtle.cfg
@@ -0,0 +1,10 @@
+width = 800
+height = 600
+canvwidth = 1200
+canvheight = 900
+shape = arrow
+mode = standard
+resizemode = auto
+fillcolor = ""
+title = Python turtle graphics demo.
+
diff --git a/Demo/turtle/turtleDemo.py b/Demo/turtle/turtleDemo.py
new file mode 100644
index 0000000..a454382
--- /dev/null
+++ b/Demo/turtle/turtleDemo.py
@@ -0,0 +1,291 @@
+#!/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
diff --git a/Demo/turtle/turtledemo_two_canvases.py b/Demo/turtle/turtledemo_two_canvases.py
new file mode 100644
index 0000000..4fdb59a
--- /dev/null
+++ b/Demo/turtle/turtledemo_two_canvases.py
@@ -0,0 +1,52 @@
+#!/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()