Bug 319004 CCE caused by PartRenderingEngine assuming a parent eContainer() is an MElementContainer
An MMenu's container could be an MPart, which leads to a CCE in createGui(MUIElement).
bundles/org.eclipse.e4.ui.workbench.swt/src/org/eclipse/e4/ui/internal/workbench/swt/PartRenderingEngine.java
if (renderer == null)
				return;
			
			if (changedElement.isVisible()
					&& changedElement.getWidget() instanceof Control) {
				
				
				Composite realComp = (Composite) renderer
						.getUIContainer(changedElement);
				Control ctrl = (Control) changedElement.getWidget();
				ctrl.setParent(realComp);
				fixZOrder(changedElement);
				renderer.childRendered(parent, changedElement);
			} else {
				
				if (changedElement.getWidget() instanceof Control) {
					Control ctrl = (Control) changedElement.getWidget();
					ctrl.setParent(getLimboShell());
				}
				renderer.hideChild(parent, changedElement);
			}
		}
	};
	private EventHandler trimHandler = new EventHandler() {
		public void handleEvent(Event event) {
			Object changedObj = event.getProperty(UIEvents.EventTags.ELEMENT);
			if (!(changedObj instanceof MTrimmedWindow))
				return;
			MTrimmedWindow window = (MTrimmedWindow) changedObj;
			if (window.getWidget() == null)