Bug 327964 EPartService's hidePart may fail when trying to hide a shared part that's in a shared container
The placeholder retrieval code in the EPartService implementation doesn't go far down deep enough and actually stops at the shared container level. This causes the placeholder of the shared part to not be found.
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/application/EPartServiceTest.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);
			applicationContext.set(IPresentationEngine.class.getName(),
					newEngine);
			engine = (IPresentationEngine) newEngine;
		}
		return engine;
	}
	public void testFindPart_PartInWindow() {