Bug 322403 Showing a shared part with PartState.VISIBLE may not work correctly due to incorrect parent comparisons
We check the parents of the active part against the part-to-be-shown to determine how to respond when PartState.VISIBLE is used but the check is always 'true' for shared parts because getParent() returns 'null' for both parts. This is obviously wrong. We need to update the code to consider placeholders.
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/PartServiceImpl.java
* This is the specific implementation. TODO: generalize it
	 */
	
	
	private MElementContainer<MUIElement> rootContainer;
	@Inject
	public void setRootContainer(@Named(EPartService.PART_SERVICE_ROOT) MElementContainer root) {
		rootContainer = root;
	}
	@Inject
	private IPresentationEngine engine;
	@Inject
	private EModelService modelService;
	@Inject
	private Logger logger;
	@Inject
	@Optional
	private ISaveHandler saveHandler;
	@Inject
	private IEventBroker eventBroker;
	private MPart activePart;
	private MPart lastActivePart;
	private ListenerList listeners = new ListenerList();
	private boolean constructed = false;
	public PartServiceImpl() {
		
	}
	@Inject
	void setPart(@Optional @Named(IServiceConstants.ACTIVE_PART) MPart p) {
		if (activePart != p) {