Bug 326177 EPartService's getActivePart() does not appear to work properly for an application with multiple windows
Based on the code in PartServiceCreationFunction, the EPartService implementation being returned when an application's context is queried seems to be a window-level EPartService implementation.
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/application/EPartServiceTest.java
.createPartDescriptor();
		partDescriptor.setCategory("containerTag");
		partDescriptor.setElementId("partId");
		partDescriptor.setAllowMultiple(true);
		application.getDescriptors().add(partDescriptor);
		MWindow window = BasicFactoryImpl.eINSTANCE.createWindow();
		application.getChildren().add(window);
		application.setSelectedElement(window);
		MPerspectiveStack perspectiveStack = AdvancedFactoryImpl.eINSTANCE
				.createPerspectiveStack();
		window.getChildren().add(perspectiveStack);
		window.setSelectedElement(perspectiveStack);
		MPerspective perspective = AdvancedFactoryImpl.eINSTANCE
				.createPerspective();
		perspective.getTags().add("containerTag");
		perspectiveStack.getChildren().add(perspective);
		perspectiveStack.setSelectedElement(perspective);
		initialize(applicationContext, application);
		getEngine().createGui(window);
		EPartService partService = window.getContext().get(EPartService.class);
		MPlaceholder placeholder = partService.createSharedPart("partId", true);
		MPart sharedPart = (MPart) placeholder.getRef();
		sharedPart.setCurSharedRef(placeholder);
		partService.showPart(sharedPart, PartState.ACTIVATE);
		assertEquals(1, perspective.getChildren().size());
		assertEquals(placeholder, perspective.getChildren().get(0));
	}
	private void testShowPart_Bug322368_Part(PartState partState) {
		MApplication application = ApplicationFactoryImpl.eINSTANCE
				.createApplication();