message: Implement and expose `Element::on_event`
diff: @@ -227,6 +227,28 @@ where
  self.widget.layout(renderer, limits)
  }
  + /// Processes a runtime [`Event`].
  + ///
  + /// [`Event`]: enum.Event.html
  + pub fn on_event(
  + &mut self,
  + event: Event,
  + layout: Layout<'_>,
  + cursor_position: Point,
  + messages: &mut Vec<Message>,
  + renderer: &Renderer,
  + clipboard: Option<&dyn Clipboard>,
  + ) {
  + self.widget.on_event(
  + event,
  + layout,
  + cursor_position,
  + messages,
  + renderer,
  + clipboard,
  + );
  + }
  +
  /// Draws the [`Element`] and its children using the given [`Layout`].
  ///
  /// [`Element`]: struct.Element.html
  