Apple's strict position on one-button mice could be set to change, as it has published a patent application – originally filed in September 2002 – for a mouse that has an optically based scrolling feature. This turned up last year as well as plans for a mouse with a rotary dial.

Instead of a traditional scroll wheel, the optical touch-pad appears to be based on the iPod's scroll-wheel or iPod's mini's click-wheel, which would make the touch-pad surface tap sensitive. The peripheral device includes "one or more buttons configured to provide a clicking action for performing actions on the display screen".

The patent application explains "the peripheral input device includes a housing and an optical touch-pad carried by the housing. The optical touch pad is configured to translate finger motion into movements on the display screen."

Finger clicking good The optical touch-pad includes an optically operable window and an optical sensor "configured to work through the optically operable window so as to detect movements of a finger in close proximity to and moving across the optically operable window." The optically operable window makes up a "substantial" portion of the translucent housing.

While Apple admits that a scroll wheel "saves time and steps", it adds that in most cases, the scroll wheel and switch require a separate mechanical component to be mounted in the mouse with portions of it protruding out of the mouse housing to allow a user's finger access".

"Although mice designs such as those work well, there are continuing efforts to improve their form, feel and functionality," states Apple in the patent. "For example, it would be desirable to provide an improved scrolling feature for a mouse that is aesthetically pleasing to the user. The scroll wheel is not aesthetically pleasing since it protrudes above the mouse housing.

"Furthermore, the scroll wheel of the mouse can only be manipulated in one direction, and thus the use of the scroll wheel becomes counter intuitive when scrolling in a different direction in the GUI. In addition, it would be desirable to provide an improved scrolling feature for a mouse that allows the mouse to scroll directly without holding down or physically moving a wheel, button, switch or the like."