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
partDescriptor.setElementId("partId");
		application.getDescriptors().add(partDescriptor);
		getEngine().createGui(window);
		EPartService partService = (EPartService) window.getContext().get(
				EPartService.class.getName());
		assertNull(partService.showPart("partId2", partState));
	}
	public void testShowPart_Id_IncorrectDescriptor_ACTIVATE() {
		testShowPart_Id_IncorrectDescriptor(PartState.ACTIVATE);
	}
	public void testShowPart_Id_IncorrectDescriptor_VISIBLE() {
		testShowPart_Id_IncorrectDescriptor(PartState.VISIBLE);
	}
	public void testShowPart_Id_IncorrectDescriptor_CREATE() {
		testShowPart_Id_IncorrectDescriptor(PartState.CREATE);
	}
	private void testShowPart_Id_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);