some mice have a per axis "sensitivity" control which adapts the hardware
resolution without changing the DPI (looking at you Etekcity and Roccat).

buttons need a couple of has_capability() functions to check which action
types and actions are possible

light support:
- on/off
- color
- patterns

some epollfd-like thing for the caller to check if events are available.
Needed for notification when the mouse changes through someone else
manipulating settings.