message: Implement `Widget::draw` for `Column`
diff: @@ -170,7 +170,9 @@ where
  cursor_position: Point,
  viewport: &Rectangle,
  ) {
  - // TODO
  + for (child, layout) in self.children.iter().zip(layout.children()) {
  + child.draw(renderer, defaults, layout, cursor_position, viewport);
  + }
  }
  fn hash_layout(&self, state: &mut Hasher) {
  