Bug 283194 [UI] StackModelFactory does not need 'engine' local
We can remove this from createWidget() final IStylingEngine engine = (IStylingEngine) folderContext .get(IStylingEngine.SERVICE_NAME); because the engine is now passed in via DI. Replace the refs to "engine" with the local "stylingEngine".
bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/workbench/ui/renderers/swt/StackRenderer.java
currentActive = child;
					}
					
					String cssClassName = (currentActive == folderContext) ? "active" 
							: "inactive"; 
					engine.setClassname(ctf, cssClassName);
					
					
					if (ctf.getTopRight() != null)
						engine.setClassname(ctf.getTopRight(), cssClassName);
					
					
					CTabItem[] items = ctf.getItems();
					for (int i = 0; i < items.length; i++) {
						stylingEngine.setClassname(items[i], cssClassName);
					}
				}
			});
		}
		return newWidget;
	}
	public void postProcess(MPart<?> part) {
		super.postProcess(part);
		if (!(part instanceof MStack))
			return;
		CTabFolder ctf = (CTabFolder) part.getWidget();
		MPart<?> selPart = ((MStack) part).getActiveChild();
		if (selPart == null)
			return;