Bug 305703 [Viewers][CommonNavigator] remembered contributions can leak when using filters
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/StructuredViewer.java
*/
	private ViewerComparator sorter;
	/**
	 * This viewer's filters (element type: <code>ViewerFilter</code>).
	 * <code>null</code> means there are no filters.
	 */
	private List filters;
	/**
	 * Indicates whether the viewer should attempt to preserve the selection
	 * across update operations.
	 * 
	 * @see #setSelection(ISelection, boolean)
	 */
	private boolean preserveSelection = true;
	/**
	 * Indicates whether a selection change is in progress on this viewer.
	 * 
	 * @see #setSelection(ISelection, boolean)
	 */
	private boolean inChange;
	
	/**
	 * Used while a selection change is in progress on this viewer to indicates
	 * whether the selection should be restored.
	 * 
	 * @see #setSelection(ISelection, boolean)
	 */
	private boolean restoreSelection;
	/**
	 * List of double-click state listeners (element type: