Bug 327044 EPartService's hidePart(*) should unset the part's parent element if the part is the selected element
It is not valid to have a selected element that's TBR flag is 'false'.
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/application/EPartServiceTest.java
EPartService.class.getName());
		partService.activate(partA);
		Object o = applicationContext.get(IServiceConstants.ACTIVE_PART);
		assertEquals(partA, o);
		partService.activate(partB);
		o = applicationContext.get(IServiceConstants.ACTIVE_PART);
		assertEquals(partB, o);
	}
	private void testShowPart_Bug307747(PartState partState) {
		MApplication application = ApplicationFactoryImpl.eINSTANCE
				.createApplication();
		MPartDescriptor partDescriptor = org.eclipse.e4.ui.model.application.descriptor.basic.impl.BasicFactoryImpl.eINSTANCE
				.createPartDescriptor();
		partDescriptor.setElementId("partId");
		partDescriptor.setCategory("category");
		application.getDescriptors().add(partDescriptor);
		final MWindow window = BasicFactoryImpl.eINSTANCE.createWindow();
		application.getChildren().add(window);
		application.setSelectedElement(window);
		
		MPartStack stack = BasicFactoryImpl.eINSTANCE.createPartStack();
		stack.setElementId("category");
		window.getChildren().add(stack);
		window.setSelectedElement(stack);
		MPart partA = BasicFactoryImpl.eINSTANCE.createPart();
		stack.getChildren().add(partA);
		stack.setSelectedElement(partA);
		
		initialize(applicationContext, application);