[From Bill Powers (2004.06.11.1437 MDT)]
But, there is something that puzzles me. In both versions when I increase
the size of formation and then exercise the disturbance something
unexpected happens. The distrubance switched on the disturbed agent moves
to the right. Switch the disturbance off the agent moves to the left and
when doing so moves outside the chalkmarks that provide a reference for
the formation. The strange thing is that the display retains this
excursion. However, when I look at the code the screen is updated using a
clearwindow or something command that I would think would blank the entire
screen.
I'm using the
"setviewport"
command in order to shorten the time it takes
to clear the display before rewriting, and to provide a place where the
"disturbance on/off" legend can stay without being erased.
That explains it-- the or "something" made the difference.