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
}
	public MPart showPart(MPart part, PartState partState) {
		Assert.isNotNull(part);
		Assert.isNotNull(partState);
		MPart addedPart = addPart(part);
		MPlaceholder localPlaceholder = getLocalPlaceholder(addedPart);
		
		if (localPlaceholder != null && addedPart.getCurSharedRef() != localPlaceholder) {
			addedPart.setCurSharedRef(localPlaceholder);
		}
		switch (partState) {
		case ACTIVATE:
			activate(addedPart);
			return addedPart;
		case VISIBLE:
			MPart activePart = getActivePart();
			if (activePart == null || getParent(activePart) == getParent(addedPart)) {
				activate(addedPart);
			} else {
				bringToTop(addedPart);
			}
			return addedPart;
		case CREATE:
			addedPart.setToBeRendered(true);
			MPlaceholder placeholder = addedPart.getCurSharedRef();
			if (placeholder != null) {
				placeholder.setToBeRendered(true);
				engine.createGui(placeholder);
				MElementContainer<MUIElement> parent = placeholder.getParent();
				if (parent.getChildren().size() == 1) {