A Buttons event generator is usually associated to a group of physical buttons and allow to generate events relating to them.
Command is an event generator that generates application-level events.
Generic event generator.
A Keyboard event generator allows key combinations to generate a key code.
Keypad is a Keyboard that defines an event generator for 12-key keypads.
A pointer event generator represents a pointing device that is usually associated to a group of physical buttons.
A states event generator is usually associated to a group of physical devices holding a position (switch, rotary wheel encoder, ...) and allows to generate events relating to them.