Physics pen color problem
completed by: Sai Vineet
mentors: Walter Bender
Weird color behavior -
* Add a box, and a pen to the box. Let some points be plotted.
* After a bit of time, remove the box, and the attached pen
* After a bit of time, remove the box, and the attached pen
* Exit using Stop button, and thus save to journal
* Restart the above journal project.
* Now add a box, and a pen to it.
* Notice that the points plotted before change color to the new box's color.