This commit introduces a naive system for sending events
when a pointer enters or leaves a pointer hit area.
Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>
For integrating with external window implementations (replacing
package app), access to the event router is required. Extract it
and put it into the new package router.
Router may belong in package io/event, but can't without introducing
import cycles.
Signed-off-by: Elias Naur <mail@eliasnaur.com>