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
initialize(applicationContext, application);
		getEngine().createGui(window);
		EPartService partService = (EPartService) window.getContext().get(
				EPartService.class.getName());
		partService.activate(partA);
		assertEquals(partA, partService.getActivePart());
		MPart shownPart = partService.showPart("partB",
				EPartService.PartState.VISIBLE);
		assertEquals(2, partStack.getChildren().size());
		assertEquals(
				"The part is in the same stack as the active part, so the active part should have changed",
				partB, partService.getActivePart());
		assertNotNull("The shown part should have a context",
				partB.getContext());
		assertFalse(partService.isPartVisible(partA));
		assertTrue(partService.isPartVisible(partB));
		assertEquals(partB, shownPart);
		assertTrue(partB.isToBeRendered());
	}
	private void testShowPart_Id_Unrendered(EPartService.PartState partState) {
		MApplication application = ApplicationFactoryImpl.eINSTANCE
				.createApplication();
		MWindow window = BasicFactoryImpl.eINSTANCE.createWindow();
		application.getChildren().add(window);
		application.setSelectedElement(window);
		MPart part = BasicFactoryImpl.eINSTANCE.createPart();
		part.setElementId("partId");
		part.setToBeRendered(false);
		window.getChildren().add(part);
		initialize(applicationContext, application);