Bug 314641 Parts in stacks do not show any content until you switch parts around
bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/workbench/ui/renderers/swt/StackRenderer.java
activationJob = null;
			if (stackToActivate != null
					&& stackToActivate.getSelectedElement() != null) {
				MUIElement selElement = stackToActivate.getSelectedElement();
				if (selElement instanceof MPlaceholder)
					selElement = ((MPlaceholder) selElement).getRef();
				activate((MPart) selElement);
			}
		}
	}
	private ActivationJob activationJob = null;
	synchronized private void activateStack(MElementContainer<MUIElement> stack) {
		CTabFolder ctf = (CTabFolder) stack.getWidget();
		if (ctf == null || ctf.isDisposed())
			return;
		if (activationJob == null) {
			activationJob = new ActivationJob();
			activationJob.stackToActivate = stack;
			ctf.getDisplay().asyncExec(activationJob);
		} else {
			activationJob.stackToActivate = stack;
		}
	}
	public StackRenderer() {
		super();
	}
	@PostConstruct
	public void init() {
		super.init(eventBroker);
		itemUpdater = new EventHandler() {