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.
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/PartServiceImpl.java
for (MInputPart p : getParts(MInputPart.class, null)) {
			if (inputUri.equals(p.getInputURI())) {
				rv.add(p);
			}
		}
		return rv;
	}
	/**
	 * "Container" here is: 1) a selected MPerspective, or, if none available 2) the MWindow for
	 * which this part service is created, or, if not available, 3) the MApplication.
	 */
	private MElementContainer<MUIElement> getContainer() {
		MElementContainer<? extends MUIElement> outerContainer = (workbenchWindow != null) ? workbenchWindow
				: application;
		
		for (MElementContainer<?> container = outerContainer; container != null;) {
			if (container instanceof MPerspective)
				return (MElementContainer<MUIElement>) container;
			Object child = container.getSelectedElement();
			if (child == null)
				break;
			if (child instanceof MElementContainer<?>)
				container = (MElementContainer<?>) child;
			else
				break;
		}
		return (MElementContainer<MUIElement>) outerContainer;
	}
}