Bug 81078 [preferences] Restore Defaults duplicates list entries
I200412142000 Restore Defaults on Java > Editor > Appearance duplicates the "Appearance color options" entries.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/preferences/AbstractConfigurationBlock.java
private final IPreferenceStore fDialogSettingsStore;
		private ExpandableComposite fFirstChild= null;
		/**
		 * Creates a new section manager.
		 */
		public SectionManager() {
			this(null, null);
		}
		/**
		 * Creates a new section manager.
		 */
		public SectionManager(IPreferenceStore dialogSettingsStore, String lastOpenKey) {
			fDialogSettingsStore= dialogSettingsStore;
			fLastOpenKey= lastOpenKey;
		}
		private void manage(ExpandableComposite section) {
			if (section == null)
				throw new NullPointerException();
			if (fSections.add(section))
				section.addExpansionListener(fListener);
		}
		
		/**
		 * Creates a new composite that can contain a set of expandable
		 * sections. A <code>ScrolledPageComposite</code> is created and a new
		 * composite within that, to ensure that expanding the sections will
		 * always have enough space, unless there already is a
		 * <code>ScrolledComposite</code> along the parent chaing of
		 * <code>parent</code>, in which case a normal <code>Composite</code>
		 * is created.