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
* <p>
		 * The receiver keeps a reference to the inner body composite, so that
		 * new sections can be added via <code>createSection</code>.
		 * </p>
		 * 
		 * @param parent the parent composite
		 * @return the newly created composite
		 */
		public Composite createSectionComposite(Composite parent) {
			Assert.isTrue(fBody == null);
			boolean isNested= isNestedInScrolledComposite(parent);
			Composite composite;
			if (isNested) {
				composite= new Composite(parent, SWT.NONE);
				fBody= composite;
			} else {
				composite= new ScrolledPageContent(parent);
				fBody= ((ScrolledPageContent) composite).getBody();
			}
			
			fBody.setLayout(new GridLayout());
			
			return composite;
		}
		
		/**
		 * Creates an expandable section within the parent created previously by
		 * calling <code>createSectionComposite</code>. Controls can be added 
		 * directly to the returned composite, which has no layout initially.
		 *