It used to be that when you dragged an item off the Dock and dropped it, the icon would disappear in a puff of smoke and make a satisfying noise. The animation was strangely primitive against the backdrop of the slick user interface of what used to called Mac OS X.
The animation first appeared in Developer Preview 4 and many thought it was a placeholder for something more polished. However, after awhile, many people seem to take a liking to it. Here’s a series of frames that shows it if you’re not familiar.
The legendary poof animation came out of a discussion of the Human Interface team that wanted this action to have an animation to go with the very liquid Aqua interface.
One of the most talented engineers on the team took out a piece of paper. I wish I could say it was a napkin to make the story better.
On the piece of paper, he drew a series of frames similar to what is pictured above. A quick, five frame animation. The intention of the designer was that these drawings would stoke further discussion. That it would get cleaned up and refined later.
But that never happened. It shipped as is. And the rest is history.