Consider the following modified oracle example code for Accordions:


===== AccordionTest.java =====

package test;

import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Accordion;
import javafx.scene.control.TitledPane;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.paint.Color;
import javafx.stage.Stage;

public class AccordionTest extends Application {

  final String[] imageNames = new String[]{"Apples", "Flowers", "Leaves"};
  final Image[] images = new Image[imageNames.length];
  final ImageView[] pics = new ImageView[imageNames.length];
  final TitledPane[] tps = new TitledPane[imageNames.length];

  public static void main(String[] args) {
    launch(args);
  }

  @Override public void start(Stage stage) {
    stage.setTitle("TitledPane");
    Scene scene = new Scene(new Group(), 80, 180);
    scene.setFill(Color.GHOSTWHITE);

    final Accordion accordion1 = new Accordion ();

    for (int i = 0; i < imageNames.length; i++) {
      images[i] = new
              Image(getClass().getResourceAsStream(imageNames[i] + ".jpg"));
      pics[i] = new ImageView(images[i]);
      tps[i] = new TitledPane(imageNames[i],pics[i]);
    }
    accordion1.getPanes().addAll(tps);

    final Accordion accordion2 = new Accordion ();

    for (int i = 0; i < imageNames.length; i++) {
      images[i] = new
              Image(getClass().getResourceAsStream(imageNames[i] + ".jpg"));
      pics[i] = new ImageView(images[i]);
      tps[i] = new TitledPane(imageNames[i],pics[i]);
    }
    accordion2.getPanes().addAll(tps);

    final Accordion accordion3 = new Accordion ();

    for (int i = 0; i < imageNames.length; i++) {
      images[i] = new
              Image(getClass().getResourceAsStream(imageNames[i] + ".jpg"));
      pics[i] = new ImageView(images[i]);
      tps[i] = new TitledPane(imageNames[i],pics[i]);
    }
    accordion3.getPanes().addAll(tps);

    final Accordion rootAccordion = new Accordion ();

    TitledPane first = new TitledPane("First", accordion1);
    TitledPane second = new TitledPane("Second", null);
    second.setGraphic(null);
    second.setCollapsible(false);
    TitledPane third = new TitledPane("Third", accordion3);
    rootAccordion.getPanes().add(first);
    rootAccordion.getPanes().add(second);
    rootAccordion.getPanes().add(third);

    Group root = (Group)scene.getRoot();
    root.getChildren().add(rootAccordion);
    stage.setScene(scene);
    stage.show();
  }
}

================

This contains nested accordions that simulate a tree like structure. When opening/closing the TitledPanes, ugly gaps appear on the animation (between the first nested Accordion and the second TitledPane of the toplevel Accordion):

http://250kb.de/u/130517/p/yobFmC94fFZV.png

This also happens with other controls, like the one in this example: https://forums.oracle.com/forums/thread.jspa?threadID=2339215

Picture:

http://250kb.de/u/130517/p/eud3gpxND0Uj.png


This effect gets worse with the level of nested Accordions.