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
assertFalse(part == part2);
	}
	private void testShowPart_Part(PartState partState) {
		MApplication application = ApplicationFactoryImpl.eINSTANCE
				.createApplication();
		MWindow window = BasicFactoryImpl.eINSTANCE.createWindow();
		application.getChildren().add(window);
		MPartDescriptor partDescriptor = org.eclipse.e4.ui.model.application.descriptor.basic.impl.BasicFactoryImpl.eINSTANCE
				.createPartDescriptor();
		partDescriptor.setElementId("partId");
		application.getDescriptors().add(partDescriptor);
		application.setSelectedElement(window);
		initialize(applicationContext, application);
		getEngine().createGui(window);
		EPartService partService = (EPartService) window.getContext().get(
				EPartService.class.getName());
		MPart part = partService.createPart("partId");
		partService.showPart(part, partState);
	}
	public void testShowPart_Part_ACTIVATE() {
		testShowPart_Part(PartState.ACTIVATE);
	}
	public void testShowPart_Part_VISIBLE() {
		testShowPart_Part(PartState.VISIBLE);
	}
	public void testShowPart_Part_CREATE() {
		testShowPart_Part(PartState.CREATE);
	}
	private void testShowPart_Part_MultipleExists(boolean multipleAllowed,
			PartState partState) {