With momentum-less scrolling, the mouse works exactly like any other scroll wheel.

The underwater mouse works accurately only when dragged across a target of black and white bars, which must be carried by the diver.

But do optical mice work any better?

The mouse works by detecting its motion across any surface in both the up/down and left/right directions.

You do realize that the mouse will work on the start screen too, right?

Mr. Hawley says his mouse will work on any surface, including even those covered with ketchup, oil or flour.

To understand how optical mice work, imagine two photographs of the same object except slightly offset from each other.

Keyboards and mice work very well for office style software.

"I haven't decided if we're going to alter some of the ways the mouse works," Ms. Doron said.

The $74.95 mouse will also work with computers running Microsoft Windows.