The original note, as written at the time
CLOSING APPLICATION WINDOWS. How about this. The window closes but it sort of animates towards the source file like it is being swallowed into a black hole.
Ongoing development
When you close a window, it should animate towards its source file, as though being swallowed into a black hole.
The animation is not decoration. It is a piece of information that currently does not exist anywhere in the interface: where did this thing come from.
Right now closing a window is a disappearance. The document vanishes and you are left with no sense of where it lived, which matters enormously in the moment after you close something you meant to keep. You then go looking, and the search is entirely reconstructing what the animation could have told you in a quarter of a second.
Direction carries meaning. A window that collapses into its own centre says nothing. A window that shrinks towards a point says there is a place, and the place is over there, and if you are quick you might see which folder it pointed at.
There is a second reading, and it is the one I like better: it makes the file system visible at the moment you stop using it. Most people have a hazy model of where their work lives, and the model is built from almost no evidence. Every close is a chance to strengthen it.
The risk is that it becomes a delay. Any animation that slows the act of closing a window will be turned off within an hour, so it has to be fast enough to read and short enough to ignore — roughly a fifth of a second, no easing that makes you wait.
The right measure: after a week, the user should be able to say where a document came from without thinking about how they know.