Bug 135284 [Viewers] API: need to add methods to StructuredViewer to support ViewerComparator
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/StructuredViewer.java
* </p>
		 * <p>
		 * If <code>setSelection</code> is called from within
		 * <code>preserveSelection</code>, the call to
		 * <code>updateSelection</code> is delayed until the end of
		 * <code>preserveSelection</code>.
		 * </p>
		 * <p>
		 * Subclasses do not typically override this method, but implement
		 * <code>setSelectionToWidget</code> instead.
		 * </p>
		 */
		Control control = getControl();
		if (control == null || control.isDisposed()) {
			return;
		}
		if (!inChange) {
			setSelectionToWidget(selection, reveal);
			ISelection sel = getSelection();
			updateSelection(sel);
			firePostSelectionChanged(new SelectionChangedEvent(this, sel));
		} else {
			restoreSelection = false;
			setSelectionToWidget(selection, reveal);
		}
	}
	/**
	 * Parlays the given list of selected elements into selections on this
	 * viewer's control.
	 * <p>