Bug 337002 EPartService leaks previously active part
A reference is kept to the previously active part. This is unnecessary. We only need it to fire events. After the deactivation events have been fired, we should no longer need to keep it lying around.
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/application/EPartServiceTest.java
assertNotNull(parent);
		perspectiveStack.setSelectedElement(perspectiveB);
		perspectiveB.getContext().activate();
		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());