As might be expected, my hypertoon has generated some interest on Synergeo, one of the eGroups frequented by Fuller Schoolers. One user found something interesting, and to me surprising. Some of the smooth motion "jitterbugging" I incorporate, where rods smoothly change position (the whole rod does, versus the progressive elongation of individual rod tips -- another kind of animation I employ) ONLY seems to work well in Python 2.4 with the experimental VPython 2.4. There's a thread on this: http://groups.yahoo.com/group/synergeo/message/21263 (is one part of it). He's responding to my: http://groups.yahoo.com/group/synergeo/message/21262 I thought it was a problem with frame rate and his Celeron 2.2, or video card. But it turns out that as soon as he changed to the experimental VPython, everything worked as I'd described. Certain kinds of motion that hadn't been apparent before, now were. Interesting. I haven't done the necessary experiments on my end to verify this is the problem. I've got everything to my satisfaction on the newest VPython on my faster computer, and tried Python 2.3 + VPython on the slower laptop. But I never tried Python 2.4 + Experimental on the laptop. Kirby