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
engine.applyStyles((Widget) widget, true);
				}
				public CSSStyleDeclaration getStyle(Object widget) {
					return engine.getStyle((Widget) widget);
				}
				public void setClassnameAndId(Object widget, String classname,
						String id) {
					((Widget) widget).setData(
							"org.eclipse.e4.ui.css.CssClassName", classname); 
					((Widget) widget).setData("org.eclipse.e4.ui.css.id", id); 
					engine.applyStyles((Widget) widget, true);
				}
			});
		} else if (cssURI != null) {
			String cssResourcesURI = (String) appContext
					.get(E4Workbench.CSS_RESOURCE_URI_ARG);
			final CSSSWTEngineImpl engine = new CSSSWTEngineImpl(display, true);
			if (cssResourcesURI != null) {
				engine.getResourcesLocatorManager().registerResourceLocator(
						new OSGiResourceLocator(cssResourcesURI.toString()));
			}
			display.setData("org.eclipse.e4.ui.css.context", appContext); 
			appContext.set(IStylingEngine.SERVICE_NAME, new IStylingEngine() {
				public void setClassname(Object widget, String classname) {
					((Widget) widget).setData(
							"org.eclipse.e4.ui.css.CssClassName", classname); 
					engine.applyStyles((Widget) widget, true);
				}
				public void setId(Object widget, String id) {
					((Widget) widget).setData("org.eclipse.e4.ui.css.id", id);