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
MApplication application = createApplication("partId");
		MWindow window = application.getChildren().get(0);
		getEngine().createGui(window);
		EPartService partService = (EPartService) window.getContext().get(
				EPartService.class.getName());
		MPart part = partService.findPart("invalidPartId");
		assertNull(part);
	}
	public void testFindPart_PartInAnotherWindow() {
		MApplication application = createApplication(
				new String[] { "partInWindow1" },
				new String[] { "partInWindow2" });
		MWindow window1 = application.getChildren().get(0);
		MWindow window2 = application.getChildren().get(1);
		getEngine().createGui(window1);
		getEngine().createGui(window2);
		EPartService partService = (EPartService) window1.getContext().get(
				EPartService.class.getName());
		MPart part = partService.findPart("partInWindow2");
		assertNull(part);
		part = partService.findPart("partInWindow1");
		assertNotNull(part);
		MPartStack partStack = (MPartStack) window1.getChildren().get(0);
		assertEquals(partStack.getChildren().get(0), part);
		partService = (EPartService) window2.getContext().get(
				EPartService.class.getName());
		part = partService.findPart("partInWindow1");
		assertNull(part);
		part = partService.findPart("partInWindow2");
		assertNotNull(part);