Bug 343003 Selection changes for shared parts may not be propagated if they were not originally rendered in the model
The search algorithm currently only iterates through containers for parts. This will not work for parts that are represented by placeholders.
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/application/ESelectionServiceTest.java
private IEclipseContext applicationContext;
	private IPresentationEngine engine;
	@Override
	protected void setUp() throws Exception {
		applicationContext = E4Application.createDefaultContext();
		super.setUp();
	}
	protected String getEngineURI() {
		return "platform:/plugin/org.eclipse.e4.ui.tests/org.eclipse.e4.ui.tests.application.HeadlessContextPresentationEngine"; 
	}
	@Override
	protected void tearDown() throws Exception {
		super.tearDown();
		applicationContext.dispose();
	}
	private IPresentationEngine getEngine() {
		if (engine == null) {
			IContributionFactory contributionFactory = (IContributionFactory) applicationContext
					.get(IContributionFactory.class.getName());
			Object newEngine = contributionFactory.create(getEngineURI(),
					applicationContext);
			assertTrue(newEngine instanceof IPresentationEngine);