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
assertTrue(partListener.isValid());
	}
	public void testEvent_PartDeactivated() {
		MApplication application = createApplication("partFront", "partBack");
		MWindow window = application.getChildren().get(0);
		MPartStack partStack = (MPartStack) window.getChildren().get(0);
		MPart partFront = (MPart) partStack.getChildren().get(0);
		MPart partBack = (MPart) partStack.getChildren().get(1);
		partStack.setSelectedElement(partFront);
		getEngine().createGui(window);
		EPartService partService = (EPartService) window.getContext().get(
				EPartService.class.getName());
		assertEquals(partFront, partService.getActivePart());
		PartListener partListener = new PartListener();
		partService.addPartListener(partListener);
		partService.activate(partBack);
		assertEquals(1, partListener.getDeactivated());
		assertEquals(partFront, partListener.getDeactivatedParts().get(0));
		assertTrue(partListener.isValid());
	}
	public void testEvent_PartDeactivated2() {
		MApplication application = ApplicationFactoryImpl.eINSTANCE
				.createApplication();
		MWindow windowA = BasicFactoryImpl.eINSTANCE.createWindow();
		MWindow windowB = BasicFactoryImpl.eINSTANCE.createWindow();
		application.getChildren().add(windowA);
		application.getChildren().add(windowB);
		application.setSelectedElement(windowA);
		MPartStack stack = BasicFactoryImpl.eINSTANCE.createPartStack();
		windowB.getChildren().add(stack);