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
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(), null);
		EPartService partService = (EPartService) window.getContext().get(
				EPartService.class.getName());
		assertEquals(success, partService.saveAll(confirm));
		assertEquals(afterDirty[0], saveablePart.isDirty());
		assertEquals(saveCalled[0], editor.wasSaveCalled());
		assertEquals(afterDirty[1], saveablePart2.isDirty());
		assertEquals(saveCalled[1], editor2.wasSaveCalled());
	}
	private void testSaveAll_NoHandlers(boolean confirm, boolean[] beforeDirty,
			boolean[] throwException) {
		testSaveAll_NoHandlers(confirm, beforeDirty,
				afterDirty(beforeDirty, throwException),
				isSuccessful(beforeDirty, throwException),
				saveCalled(beforeDirty, throwException), throwException);
	}
	public void testSaveAll_NoHandlers_T_TT_TT() {