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 ChangeElement getParent() {
		return fParent;
	}
	
	/**
	 * Returns the viewer descriptor used to present a preview of this change element
	 * 
	 * @return the viewer suitable to present a preview of this change or
	 *  <code>null</code> if no previewer is configured.
	 * 
	 * @throws CoreException if an error occurred while creating the descriptor
	 */
	public abstract ChangePreviewViewerDescriptor getChangePreviewViewerDescriptor() throws CoreException;
	
	/**
	 * Feeds the input that corresponds to this change element into the
	 * given viewer. 
	 * 
	 * @param viewer the viewer to feed the input into
	 * @param categories the group categories to filter for or 
	 *  <code>null</code> if no filtering should take place
	 * 
	 * @throws CoreException if an error occurred while feeding the input
	 */
	public abstract void feedInput(IChangePreviewViewer viewer, List categories) throws CoreException;
	
	/**
	 * Returns the change directly associated with this change element or <code
	 * null</code> if the element isn't associated with a change.