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
partDescriptor.setElementId("partId");
		application.getDescriptors().add(partDescriptor);
		stack.setSelectedElement(part);
		window.setSelectedElement(stack);
		application.setSelectedElement(window);
		getEngine().createGui(window);
		EPartService partService = (EPartService) window.getContext().get(
				EPartService.class.getName());
		MPart shownPart = partService.showPart("partId", partState);
		assertNotNull(shownPart);
		assertEquals(part, shownPart);
	}
	public void testShowPart_Id_MultipleExists_TrueACTIVATE() {
		testShowPart_Id_MultipleExists(true, PartState.ACTIVATE);
	}
	public void testShowPart_Id_MultipleExists_FalseACTIVATE() {
		testShowPart_Id_MultipleExists(false, PartState.ACTIVATE);
	}
	public void testShowPart_Id_MultipleExists_TrueVISIBLE() {
		testShowPart_Id_MultipleExists(true, PartState.VISIBLE);
	}
	public void testShowPart_Id_MultipleExists_FalseVISIBLE() {
		testShowPart_Id_MultipleExists(false, PartState.VISIBLE);
	}
	public void testShowPart_Id_MultipleExists_TrueCREATE() {
		testShowPart_Id_MultipleExists(true, PartState.CREATE);
	}
	public void testShowPart_Id_MultipleExists_FalseCREATE() {
		testShowPart_Id_MultipleExists(false, PartState.CREATE);
	}