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
assertTrue("Shown part should be visible", part.isVisible());
	}
	public void testShowPart_Id_ACTIVATE_DefinedCategoryStackNotExists() {
		MApplication application = ApplicationFactoryImpl.eINSTANCE
				.createApplication();
		MWindow window = BasicFactoryImpl.eINSTANCE.createWindow();
		application.getChildren().add(window);
		application.setSelectedElement(window);
		MPartDescriptor partDescriptor = org.eclipse.e4.ui.model.application.descriptor.basic.impl.BasicFactoryImpl.eINSTANCE
				.createPartDescriptor();
		partDescriptor.setCategory("categoryId");
		partDescriptor.setElementId("partId");
		application.getDescriptors().add(partDescriptor);
		partDescriptor = org.eclipse.e4.ui.model.application.descriptor.basic.impl.BasicFactoryImpl.eINSTANCE
				.createPartDescriptor();
		partDescriptor.setCategory("categoryId");
		partDescriptor.setElementId("partId2");
		application.getDescriptors().add(partDescriptor);
		initialize(applicationContext, application);
		getEngine().createGui(window);
		EPartService partService = (EPartService) window.getContext().get(
				EPartService.class.getName());
		MPart part = partService.showPart("partId", PartState.ACTIVATE);
		assertEquals(1, window.getChildren().size());
		assertTrue(window.getChildren().get(0) instanceof MPartStack);
		MPartStack stack = (MPartStack) window.getChildren().get(0);
		assertTrue(stack.getTags().contains("categoryId"));
		assertEquals(1, stack.getChildren().size());
		assertEquals(part, stack.getChildren().get(0));
		assertEquals(part, stack.getSelectedElement());