Bug 329482 Uninstantiated part may be rendered when closing another part in the same stack
1. Activate the 'Javadoc' view. 2. Activate the 'Package Explorer' view. 3. Shutdown. 4. Restart. 5. Ctrl+3 > Properties 6. Hide the 'Properties' view. 7. Now the 'Problems' view is the selected element. It should be the 'Javadoc' view.
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/application/EPartServiceTest.java
MPart part = partService.showPart("partId", PartState.ACTIVATE);
		assertNotNull(part);
		assertEquals("partId", part.getElementId());
		assertEquals(part, partService.getActivePart());
		assertTrue("Shown part should be visible", part.isVisible());
	}
	public void testShowPart_Id_ACTIVATE_DefinedCategoryStackNotExists() {
		MApplication application = ApplicationFactoryImpl.eINSTANCE
				.createApplication();
		MWindow window = BasicFactoryImpl.eINSTANCE.createWindow();
		application.getChildren().add(window);
		application.setSelectedElement(window);
		MPartDescriptor partDescriptor = org.eclipse.e4.ui.model.application.descriptor.basic.impl.BasicFactoryImpl.eINSTANCE
				.createPartDescriptor();
		partDescriptor.setCategory("categoryId");
		partDescriptor.setElementId("partId");
		application.getDescriptors().add(partDescriptor);
		partDescriptor = org.eclipse.e4.ui.model.application.descriptor.basic.impl.BasicFactoryImpl.eINSTANCE
				.createPartDescriptor();
		partDescriptor.setCategory("categoryId");
		partDescriptor.setElementId("partId2");
		application.getDescriptors().add(partDescriptor);
		initialize(applicationContext, application);
		getEngine().createGui(window);
		EPartService partService = (EPartService) window.getContext().get(
				EPartService.class.getName());
		MPart part = partService.showPart("partId", PartState.ACTIVATE);
		assertEquals(1, window.getChildren().size());
		assertTrue(window.getChildren().get(0) instanceof MPartStack);
		MPartStack stack = (MPartStack) window.getChildren().get(0);