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
public void handleEvent(Event event) {
				MUIElement element = (MUIElement) event
						.getProperty(UIEvents.EventTags.ELEMENT);
				if (!(element instanceof MPart))
					return;
				MPart part = (MPart) element;
				String attName = (String) event
						.getProperty(UIEvents.EventTags.ATTNAME);
				Object newValue = event
						.getProperty(UIEvents.EventTags.NEW_VALUE);
				
				if (element.getParent() != null
						&& element.getParent().getRenderer() == StackRenderer.this) {
					CTabItem cti = findItemForPart(element, element.getParent());
					if (cti != null) {
						updateTab(cti, part, attName, newValue);
					}
					return;
				}
				
				
				List<MPlaceholder> refs = ElementReferenceRenderer
						.getRenderedPlaceholders(element);
				for (MPlaceholder ref : refs) {
					MElementContainer<MUIElement> refParent = ref.getParent();
					if (refParent.getRenderer() instanceof StackRenderer) {
						CTabItem cti = findItemForPart(ref, refParent);
						if (cti != null) {
							updateTab(cti, part, attName, newValue);
						}