@Test
public void testOpaque() {

    JXTitledPanel titledPanel = new JXTitledPanel();
    boolean opaque = titledPanel.isOpaque(); 
    titledPanel.setOpaque(!opaque);
    assertEquals("sanity: opaqueness toggled: ", !opaque, titledPanel.isOpaque());
    titledPanel.updateUI();
    assertEquals("ui must not overwrite custom setting: ", !opaque, titledPanel.isOpaque());
}