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
MPart part = partService.createPart("partId");
		partService.showPart(part, partState);
	}
	public void testShowPart_Part_ACTIVATE() {
		testShowPart_Part(PartState.ACTIVATE);
	}
	public void testShowPart_Part_VISIBLE() {
		testShowPart_Part(PartState.VISIBLE);
	}
	public void testShowPart_Part_CREATE() {
		testShowPart_Part(PartState.CREATE);
	}
	private void testShowPart_Part_MultipleExists(boolean multipleAllowed,
			PartState partState) {
		MApplication application = createApplication("partId");
		MWindow window = application.getChildren().get(0);
		MPartStack stack = (MPartStack) window.getChildren().get(0);
		MPart part = (MPart) stack.getChildren().get(0);
		MPartDescriptor partDescriptor = org.eclipse.e4.ui.model.application.descriptor.basic.impl.BasicFactoryImpl.eINSTANCE
				.createPartDescriptor();
		partDescriptor.setAllowMultiple(multipleAllowed);
		partDescriptor.setElementId("partId");
		application.getDescriptors().add(partDescriptor);
		stack.setSelectedElement(part);
		window.setSelectedElement(stack);
		application.setSelectedElement(window);
		getEngine().createGui(window);
		EPartService partService = (EPartService) window.getContext().get(
				EPartService.class.getName());
		MPart createdPart = partService.createPart("partId");