scroll wheel is zooming instead of scrolling

It had a thumb-operated combined analog button/ toggle switch on the side for smooth scrolling.

The earliest known example of the former is the Mighty Mouse prototype developed jointly by NTT, Japan and ETH Zürich, Switzerland (Kunio Ōno, Ken'ichi Fukaya and Jürg Nievergelt) in 1985. Other scrolling controls on a mouse, and the use of a wheel for scrolling both precede the combination of wheel and mouse. The scroll wheel on a mouse has been invented multiple times by different people unaware of the others' work. Some user interfaces, like Cinnamon (desktop environment), allow using it to adjust brightness and volume by pointing at the respective taskbar icon while scrolling. However, non-wheeled mice are still available. Scroll wheels are prevalent on modern computer mice and have become an integral part of the hardware interface. The wheel is often, but not always, engineered with detents to turn in discrete steps, rather than continuously as an analog axis, to allow the operator to more easily intuit how far they are scrolling. Some mice can scroll horizontally as well as vertically, using a tilting scroll-wheel, or additional wheel on a perpendicular axis located elsewhere on the mouse. On a mouse, the scroll-wheel can often also be used as a third mouse button by pressing down on it – a scroll button.

In other configurations (sometimes called 'natural scrolling') the effect is inverted. In a graphical user interface, the 'upward' motion moves contents of the window downward (and the scrollbar thumb, if present, upward), and vice versa. Most often, rolling the upper side of the wheel away from your body is to scroll 'upward' or 'forward', and the reverse direction is to scroll 'downward' or 'backward'.

Scroll wheel is zooming instead of scrolling