Bug 322403 Showing a shared part with PartState.VISIBLE may not work correctly due to incorrect parent comparisons
We check the parents of the active part against the part-to-be-shown to determine how to respond when PartState.VISIBLE is used but the check is always 'true' for shared parts because getParent() returns 'null' for both parts. This is obviously wrong. We need to update the code to consider placeholders.
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/application/EPartServiceTest.java
MWindow window = application.getChildren().get(0);
		MPartStack partStack = (MPartStack) window.getChildren().get(0);
		MPart partFront = (MPart) partStack.getChildren().get(0);
		MPart partBack = (MPart) partStack.getChildren().get(1);
		partStack.setSelectedElement(partFront);
		getEngine().createGui(window);
		EPartService partService = (EPartService) window.getContext().get(
				EPartService.class.getName());
		assertEquals(partFront, partService.getActivePart());
		PartListener partListener = new PartListener();
		partService.addPartListener(partListener);
		partService.activate(partBack);
		assertEquals(1, partListener.getActivated());
		assertEquals(partBack, partListener.getActivatedParts().get(0));
		assertTrue(partListener.isValid());
	}
	public void testEvent_PartActivated2() {
		MApplication application = ApplicationFactoryImpl.eINSTANCE
				.createApplication();
		MWindow windowA = BasicFactoryImpl.eINSTANCE.createWindow();
		MWindow windowB = BasicFactoryImpl.eINSTANCE.createWindow();
		application.getChildren().add(windowA);
		application.getChildren().add(windowB);
		application.setSelectedElement(windowA);
		MPartStack stack = BasicFactoryImpl.eINSTANCE.createPartStack();
		windowB.getChildren().add(stack);
		windowB.setSelectedElement(stack);
		MPart partA = BasicFactoryImpl.eINSTANCE.createPart();
		MPart partB = BasicFactoryImpl.eINSTANCE.createPart();
		stack.getChildren().add(partA);