message: Fix the delayed close in the unbuffered events example
  On linux, the window would not close after pressing the
  button until after the mouse was moved. This resulted in
  a SendError panic due to the events receiver shutting
  down before the sender.
diff: @@ -62,6 +62,7 @@ fn handle_window_event(render_context: &mut RenderContext, event: glfw::WindowEv
  match event {
  glfw::WindowEvent::Close | glfw::WindowEvent::Key(Key::Escape, _, Action::Press, _) => {
  render_context.set_should_close(true);
  + render_context.post_empty_event();
  }
  _ => {}
  }
  