>> There is also the problem when using say a very white sprite on a black
>> background, the phosphor fade of your monitor as the pixels are lit. They
>> take small time to go "black" again.
>> 
>My monitor is LCD.

Bingo! LCD's have a definite time lag between 'frames'. A common example 
is "cursor tunnelling" or "cursor trails" when you move the mouse quickly 
- you'll see a streak instead of precise 'movement'.

GWorld Tutor was written on an iBook, and I had to slow down the example 
animations to avoid just this. On my G3 at home (even with a flat-screen, 
since it's 'newer technology', faster refresh rate) I don't see the 
streaking.

I'm _extremely_ pressed for time right now - major software upgrade 
shipping 2/18, so 80-hour weeks - but if you'd like me to look at your 
code, send it to me privately. No guarantee when/if I'll get a chance, 
though.

Bill