Bug 327933 Unrendering container with invalid selectedElement can cause target element to be unrendered
bundles/org.eclipse.e4.ui.workbench.swt/src/org/eclipse/e4/ui/internal/workbench/swt/PartRenderingEngine.java
MElementContainer<?> parent = changedElement.getParent();
			
			if (parent == null && changedElement instanceof MWindow) {
				parent = (MElementContainer<?>) ((EObjectImpl) changedElement)
						.eContainer();
			}
			
			if (parent == null || parent.getWidget() == null)
				return;
			if (changedElement.isToBeRendered()) {
				Activator.trace(Policy.DEBUG_RENDERER, "visible -> true", null); 
				
				Widget w = (Widget) createGui(changedElement);
				if (w instanceof Control && !(w instanceof Shell)) {
					fixZOrder(changedElement);
				}
			} else {
				Activator
						.trace(Policy.DEBUG_RENDERER, "visible -> false", null); 
				
				removeGui(changedElement);
			}
		}
	};
	private EventHandler visibilityHandler = new EventHandler() {
		public void handleEvent(Event event) {
			MUIElement changedElement = (MUIElement) event
					.getProperty(UIEvents.EventTags.ELEMENT);
			if (!(changedElement.getWidget() instanceof Control))
				return;