window.go
func (w *Window) render() {
	w.mgr.Render(w)

	// iterate over widgets
	for _, widget := range w.widgets {
		widget.Render()
	}

	// focus on a widget
	w.focusWidget()
}
func (w *Window) render() {
	w.mgr.Render(w)

	// iterate over widgets
	for _, widget := range w.widgets {
		widget.Render()
	}

	// focus on a widget
	w.focusWidget()
}
// render calls the user provided Render and than renders the widgets in the
// window.