Long story short: To scroll start slow, to swipe act fast.
How scrolling works
If you touch the Magic Mouse surface with one or two fingers and move your finger(s) slowly an accumulated threshold distance over time, our driver switches to scroll-mode. Now scroll as fast as you like, scroll-mode stays active as long as you lift all fingers.
Accidental scrolling
It may happen that you rest your fingers on the mouse surface and move them unintentionally. If it's more than the threshold distance the driver turns on scroll mode. If this happens to you, lift all fingers to turn scrolling off.
- Adjust that threshold distance with the Sense slider to avoid accidental scrolling.
How swiping works
To swipe you need to lift all fingers. Now touch the surface and move your finger(s) fast and lift them again. A swipe is triggered only if the distance between touch reports was far enough. Actually you need to flick your finger(s).
Accidental swiping
It may happen that you like to scroll but start to fast and trigger a swipe instead.
- Adjust that swipe trigger distance with the Sense slider to make swiping easier or to avoid accidental scrolling.
Technical details
The surface of a Magic Mouse is basically a very sensitive touchpad, it is in fact the very same as a Magic Trackpad, but made of acrylic plastic.
The slightest touch of any finger, or even just hovering 1 millimeter above the surface, will create a constant stream of touch data transmitted wirelessly via Bluetooth to the computer.
There are 90 touch reports per second for a maximum of 6 fingers, which is about 9.5 kByte or 76 kBit per second. That was internet modem speed back in the 90's.
This data is processed by our driver and translated into mouse scroll events to emulate real scroll wheel(s)..
If you always rest your finger(s) on the surface, you drain the battery much quicker. To save battery, touch the mouse only at the sides in case you only like to move the mouse pointer.