Why does Dashboard slide the desktop?

Or ‘if it was a carousel, would it have still moved?’

When Walt Disney World was being constructed, one of the merry-go-rounds was installed a few inches off center. While this might not sound like a big deal, it was to Disney. At the time, it was reckoned that 5% of all the photographs taken in North America were taken at Disney theme parks, and that a large number of these would be taken from a position which would include the carousel in the background. In the background, but slightly off-center, as it was supposed to be perfectly aligned with the central axis of the castle, through whose gates many of these photographs would be taken. Rather than accept the possibility that guests would have vacation pictures that weren’t as great as they could be, the merry-go-round was moved.

So, knowing that a merry-go-round was moved a few inches in the pursuit of perfection, my almost totally un-related question is ‘why does the desktop move when I'm managing widgets in Dashboard?‘

1This shows the normal desktop, just before hitting ‘F12’…

2…everything darkens, the widgets fly in. We're just about to hit the big ‘+’ button…

3…and lots of things happen at once. Holding down the ‘shift’ key while hitting the big ‘+’ button reveals it all in slow motion. The darkened desktop moves up, revealing a cheese-grater grille underneath, on to which the widgets fly in from the left. The big ‘+’ button slides up with the desktop, whilst simultaneously rotating through 135° to become a big ‘x’ button, while the 'Manage widgets…' button fades in as it move up. And if you have either a large number of widgets, or a small monitor, a ‘1 of 2’ button also appears. Finally, as the desktop moves up, any widget that would overlap the newly-revealed cheese-grater grille gets swept up in the upward motion — notice how the weather widget has slid under the clock.

That so much happens in such an elegant way is a testament to the design that goes into Mac OS X, and I have to confess to spending slightly too much time just watching the effect in slow-motion, but I do have a couple of questions. The first — and slightly quicker — is why do the widgets fly in not from the very edges of the screen, but from an invisible gap or slot some 32 pixels in from the edge?

The second, and slightly deeper question, is this: why does the darkened desktop, with the dock, my windows, and all the other non-widgety things on it, have to move? As far as I'm concerned, the widgets are floating above my desktop — I mean, when I hit ‘F12’ they flew in from some point just over my left shoulder to land on the desktop. But when I hit the big ‘+’ button to manage widgets my darkened desktop, and everything on it, slides up to reveal that underneath it all has been this secret drawer of widgets, assembled out of a strip of metal left over from a PowerMac G5 case.

I’m now left thinking that my desktop is somehow sandwiched between a secret drawer of widgets, and the floating widgets that appeared from over my shoulder. I’m also wondering what would happen if the desktop could be persuaded to move up any further — are there more secret things hidden under there? Wouldn’t it have been simpler if the widget drawer had appeared on top of my desktop — where all the other widgets are already? How about if the drawer, and the ‘+/x’ button, and the ‘manage widgets…’ button had all just slid in from the bottom of the screen? That way the illusion wouldn’t have been broken — the widget layer would now be entirely floating above my desktop, and nothing I do in the widget layer affects the underlying desktop layer — except for clicking to return to it, of course.

The end result is less distraction, as my desktop and everything on it stays where it was, and slightly less clutter.

Going back to carousels, I can’t help wondering if the desktop’s move doesn’t make it 116 pixels off center.