Did you get to the site? You have to click/drag on the page to make a line. Release, move, repeat.
LMK if the link doesn't work. I had to reattach it a couple of times...:-)
It's interesting to build an inescapable box, and then watch the way the program deletes some of the balls, so as not to overload it's ability to keep track of them...
I positioned a line about an inch below the ball drop point, and then a line about half an inch above the same point, both lines perfectly level so that the balls go only straight up and down. None go bouncing off to the right or left. Built kind of a visual feedback loop.
God, what an annoying racket. I think I'll make it my new ringtone.
Try it sometime. It's interesting to hear the slow, deep, gong-like tones while the high-pitched rapidly-repeating tones increase in pitch and frenzy. Like a few calm, rational people in a room full of arguing dingbats. Reminds me of one of my family reunions.