Bug 327964 EPartService's hidePart may fail when trying to hide a shared part that's in a shared container
The placeholder retrieval code in the EPartService implementation doesn't go far down deep enough and actually stops at the shared container level. This causes the placeholder of the shared part to not be found.
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/application/EPartServiceTest.java
boolean[] beforeDirty, boolean[] afterDirty, boolean success,
			boolean[] saveCalled, boolean[] throwException) {
		MApplication application = ApplicationFactoryImpl.eINSTANCE
				.createApplication();
		MWindow window = BasicFactoryImpl.eINSTANCE.createWindow();
		application.getChildren().add(window);
		final MPart saveablePart = createSaveablePart(window, beforeDirty[0]);
		final MPart saveablePart2 = createSaveablePart(window, beforeDirty[1]);
		
		initialize(applicationContext, application);
		getEngine().createGui(window);
		ClientEditor editor = (ClientEditor) saveablePart.getObject();
		editor.setThrowException(throwException[0]);
		ClientEditor editor2 = (ClientEditor) saveablePart2.getObject();
		editor2.setThrowException(throwException[1]);
		window.getContext().set(ISaveHandler.class.getName(),
				new ISaveHandler() {
					public Save[] promptToSave(Collection<MPart> saveableParts) {
						int index = 0;
						Save[] prompt = new Save[saveableParts.size()];
						Iterator<MPart> it = saveableParts.iterator();
						while (it.hasNext()) {
							prompt[index] = prompt(returnValues, it.next(),
									saveablePart);
							index++;
						}
						return prompt;
					}
					public Save promptToSave(MPart saveablePart) {
						return null;