Bug 93400 LTK UI should provide official API for structural content in the preview page
org.eclipse.ltk.ui.refactoring/src/org/eclipse/ltk/internal/ui/refactoring/ChangeElement.java
public final static int INACTIVE=		0;
	
	public final static int PARTLY_ACTIVE=	1;	
	
	public final static int ACTIVE=			2;
	
	protected final static int[][] ACTIVATION_TABLE= new int[][] {
										
				{	INACTIVE,		PARTLY_ACTIVE,		PARTLY_ACTIVE },
			{	PARTLY_ACTIVE, 	PARTLY_ACTIVE,		PARTLY_ACTIVE },
				{	PARTLY_ACTIVE, 	PARTLY_ACTIVE,		ACTIVE}
	};
	
	protected static final ChangeElement[] EMPTY_CHILDREN= new ChangeElement[0];
	
	private ChangeElement fParent;
	/**
	 * Creates a new <code>ChangeElement</code> with the
	 * given parent
	 * 
	 * @param parent the change element's parent or <code>null
	 * 	</code> if the change element doesn't have a parent
	 */
	public ChangeElement(ChangeElement parent) {
		fParent= parent;
	}
	/**
	 * Returns the change element's parent.
	 * 
	 * @return the change element's parent