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
public void testShowPart_Bug322368_Placeholder_CREATE() {
		testShowPart_Bug322368_Placeholder(PartState.CREATE);
	}
	public void testShowPart_Bug322403_A() {
		MApplication application = ApplicationFactoryImpl.eINSTANCE
				.createApplication();
		MPartDescriptor partDescriptor = org.eclipse.e4.ui.model.application.descriptor.basic.impl.BasicFactoryImpl.eINSTANCE
				.createPartDescriptor();
		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();
		perspectiveStack.getChildren().add(perspective);
		perspectiveStack.setSelectedElement(perspective);
		MPartStack partStackA = BasicFactoryImpl.eINSTANCE.createPartStack();
		perspective.getChildren().add(partStackA);
		perspective.setSelectedElement(partStackA);
		MPlaceholder placeholderA = AdvancedFactoryImpl.eINSTANCE
				.createPlaceholder();
		partStackA.getChildren().add(placeholderA);
		partStackA.setSelectedElement(placeholderA);
		MPart partA = BasicFactoryImpl.eINSTANCE.createPart();