message: Track `cursor_position` in `Runtime`
diff: -use crate::{Column, Element, Event, Layout, MouseCursor, Point};
  +use crate::{input::mouse, Column, Element, Event, Layout, MouseCursor, Point};
  use std::hash::Hasher;
  use stretch::result;
  @@ -30,6 +30,13 @@ impl Runtime {
  }
  pub fn on_event(&mut self, event: Event) {
  + match event {
  + Event::Mouse(mouse::Event::CursorMoved { x, y }) => {
  + self.cursor_position = Point::new(x, y);
  + }
  + _ => {}
  + }
  +
  self.events.push(event);
  }
  