@Test
public void canIterateAncestors() throws Exception {

  JPanel panel1 = new JPanel();
  JPanel panel11 = new JPanel();
  JPanel panel12 = new JPanel();
  JPanel panel123 = new JPanel();
  JPanel panel13 = new JPanel();
  panel1.add(panel11);
  panel1.add(panel12);
  panel12.add(panel123);
  panel1.add(panel13);
  int count = 0;
  TreeWalker treeWalker = new TreeWalker(panel123);
  for (Component c : treeWalker.ancestors()) {
    count++;
  }
  assertThat(count).isEqualTo(3); // panel123, panel12, panel1
}