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
MElementContainer<MUIElement> match = findContainer((MElementContainer<?>) child,
						element);
				if (match != null) {
					return match;
				}
			}
		}
		return null;
	}
	private MUIElement getRemoveTarget(MPart part) {
		MPlaceholder placeholder = getLocalPlaceholder(part);
		return placeholder == null ? part : placeholder;
	}
	public MPart addPart(MPart part) {
		Assert.isNotNull(part);
		MPart localPart = findPart(part.getElementId());
		return addPart(part, localPart == null ? part : localPart);
	}
	public MPart showPart(String id, PartState partState) {
		Assert.isNotNull(id);
		Assert.isNotNull(partState);
		MPart part = findPart(id);
		if (part == null) {
			MPartDescriptor descriptor = findDescriptor(id);
			part = createPart(descriptor);
			if (part == null) {
				return null;
			}
		}
		return showPart(addPart(part), partState);