Hi...

See this project in

http://www.squeakland.org/project.jsp? http://www.squeakland.org/uploads/Spirograph%203.005.pr

The green circle is embedded in the yellow rectangle, the yellow rectangle is embedded in the red one and the red is embedded in the blue one. The blue, red and yellow rectangles have a non-default center of rotation. The green circle has the pen down.

Each time the blue rectangle get heading in 0 degrees and the others rectangles have non-zero headings, the pen trail get corrupted.

With blue rotation speed in 10, red in -6 and yellow in 5 the error happens a lot of times. Just put this numbers in the sliders, press go and wait.

TIA,

Diego Gomez Deck http://www.small-land.org