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
public void testShowPart_Id_Unrendered_ACTIVATE3() {
		testShowPart_Id_Unrendered3(PartState.ACTIVATE);
	}
	private void testShowPart_Id_PartAlreadyShown(PartState partState) {
		MApplication application = createApplication(1, new String[1][0]);
		MWindow window = application.getChildren().get(0);
		MPartDescriptor partDescriptor = org.eclipse.e4.ui.model.application.descriptor.basic.impl.BasicFactoryImpl.eINSTANCE
				.createPartDescriptor();
		partDescriptor.setElementId("partId");
		application.getDescriptors().add(partDescriptor);
		getEngine().createGui(window);
		EPartService partService = (EPartService) window.getContext().get(
				EPartService.class.getName());
		MPart part = partService.showPart("partId", partState);
		assertNotNull(part);
		assertEquals("partId", part.getElementId());
		assertEquals(part, partService.getActivePart());
		MPart part2 = partService.showPart("partId", partState);
		assertEquals("Should not have instantiated a new MPart", part, part2);
		assertEquals(part, partService.getActivePart());
	}
	public void testShowPart_Id_PartAlreadyShown_ACTIVATE() {
		testShowPart_Id_PartAlreadyShown(PartState.ACTIVATE);
	}
	public void testShowPart_Id_PartAlreadyShown_CREATE() {
		testShowPart_Id_PartAlreadyShown(PartState.CREATE);
	}
	public void testShowPart_Id_PartAlreadyShown_VISIBLE() {
		testShowPart_Id_PartAlreadyShown(PartState.VISIBLE);
	}