Event
interface Event
Events are how PolyUI communicates between components and to the user.
Everything from mouse clicks, key presses, text input changes, initialization and destruction of components are communicated through events.
These events can be dispatched by your own components, and you can add your own events - though PolyUI comes with 22 events by default.
event specificity
Some events are specific, requiring constructor parameters to ensure that for example, only single, left-click events are handled by any given handler. others are non-specific, like Focused.UnmappedInput and receive any matching event of the type.
by default, an event is non-specific. in order to make it specific, override the equals and hashCode methods.