To show this problem:

Make a LineMorph.
Make it have one arrowhead.
Customize the arrowheads so it's an open arrowhead about the same size as the 
default (arrowSpec: 4 at -5).
Make the handles appear.
Grab the handle away from the arrowhead.
Rotate the line slowly in a circle.

You will see the arrowhead leaving behind graphical trash.

-- 
Ned Konz
currently: Stanwood, WA
email:     ned at bike-nomad.com
homepage:  http://bike-nomad.com