Bug 137849 Unable to set comparator in StructuredViewer
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/StructuredViewer.java
* the viewer's input element.
	 * </p>
	 * 
	 * @return the root element, or <code>null</code> if none
	 */
	protected Object getRoot() {
		return getInput();
	}
	/**
	 * The <code>StructuredViewer</code> implementation of this method returns
	 * the result as an <code>IStructuredSelection</code>.
	 * <p>
	 * Subclasses do not typically override this method, but implement
	 * <code>getSelectionFromWidget(List)</code> instead.
	 * <p>
	 * @return ISelection
	 */
	public ISelection getSelection() {
		Control control = getControl();
		if (control == null || control.isDisposed()) {
			return StructuredSelection.EMPTY;
		}
		List list = getSelectionFromWidget();
		return new StructuredSelection(list);
	}
	/**
	 * Retrieves the selection, as a <code>List</code>, from the underlying
	 * widget.
	 * 
	 * @return the list of selected elements