Bug 326087 StackRenderer arbitrarily changes selected element when MPartStack is being unrendered
1. Open two files. 2. Activate the editor in the back. 3. Restart 4. The file in the wrong is active now. :O
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/workbench/PartRenderingEngineTests.java
.createPerspectiveStack();
		window.getChildren().add(perspectiveStack);
		window.setSelectedElement(perspectiveStack);
		MPerspective perspective = AdvancedFactoryImpl.eINSTANCE
				.createPerspective();
		perspectiveStack.getChildren().add(perspective);
		perspectiveStack.setSelectedElement(perspective);
		MPlaceholder placeholder = AdvancedFactoryImpl.eINSTANCE
				.createPlaceholder();
		placeholder.setRef(part);
		part.setCurSharedRef(placeholder);
		perspective.getChildren().add(placeholder);
		perspective.setSelectedElement(placeholder);
		application.setContext(appContext);
		appContext.set(MApplication.class.getName(), application);
		wb = new E4Workbench(application, appContext);
		wb.createAndRunUI(window);
		assertNotNull(part.getObject());
		appContext.get(IPresentationEngine.class).removeGui(perspective);
		assertNull(part.getObject());
	}
	public void testBug324839() throws Exception {
		MApplication application = ApplicationFactoryImpl.eINSTANCE
				.createApplication();
		application.setContext(appContext);
		MWindow window = BasicFactoryImpl.eINSTANCE.createWindow();
		application.getChildren().add(window);
		application.setSelectedElement(window);
		MPartStack partStack = BasicFactoryImpl.eINSTANCE.createPartStack();
		window.getChildren().add(partStack);