Bug 322368 Sole part in a part stack shown by EPS should be set as the selected element
SSIA
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/application/EPartServiceTest.java
perspectiveStack.setSelectedElement(perspectiveB);
		window.getContext().set(IContextConstants.ACTIVE_CHILD,
				perspectiveB.getContext());
		MPart part2 = partService.showPart("partId", PartState.ACTIVATE);
		parent = part2.getParent();
		while (parent != null) {
			if (parent == perspectiveB) {
				break;
			} else if (parent == perspectiveA) {
				fail("Parent should not have been perspectiveA");
			}
			parent = parent.getParent();
		}
		assertNotNull(parent);
		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());