Thorough testing revealesd the following bugs in turtle.py (Python 2.6):

1) Around lines 359 and 379: There's a name conflict with a methodname
of the parentclass Frame: _root. The bugfix consists in renaming this
attribute, which occurs only twice

2) Around line 732: Turtles with image-shapes do not recognize user
coordinates. This is fixed in  TurtleScreenBase method _drawimage by
introducing the corresponding scaling factors

3) Around line 3570: Calling the __init__ - Method of the Screen-class
(which uses the Borg idiom) destroys graphics and Turtles on the Screen.
This is an undesired behaviour. The fix brings the behaviour of Screen
in accordance with the Python 3.0 version.

4) Around line 3612: Screen.setup() needs a final update() call in order
to ensure, that immediately following calls of window_width() or
window_height() return correct values.

Moreover there is a correction of the version number and date

Bugfixes are attached in turtle.py.diff

Regards,
Gregor