private void posizionaComponenti() { // (3)
   HBox left = new HBox();
   HBox right = new HBox(8);
   this.setCenter(labelTitolo);
   right.setPadding(new Insets(0, 16, 0, 0));
   right.setAlignment(Pos.CENTER);
   right.getChildren().addAll(save);
   left.setMinWidth(60);
   left.setMaxWidth(60);
   this.setRight(right);
   this.setLeft(left);
 }