When setting a mouse to left-handed, this affects all connected
mice. This, however, is very trouble-some with Apple laptops
because their touchpad only has a single button which will
suddenly be a right button rather than stay a left button.
Normally, for the left button a two- or three-finger touch
is configured with synaptics instead.

This means that it is not possible to use a left-handed mouse
along with the touchpad on such machines without switching the
mouse to right-handed whenever using the touchpad and to
left-handed for using a mouse.