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
public void testSavePart_CancelFalseTrueTrue() {
		testSavePart(ISaveHandler.Save.CANCEL, false, true, true);
	}
	public void testSavePart_CancelFalseTrueFalse() {
		testSavePart(ISaveHandler.Save.CANCEL, false, true, false);
	}
	public void testSavePart_CancelFalseFalseTrue() {
		testSavePart(ISaveHandler.Save.CANCEL, false, false, true);
	}
	public void testSavePart_CancelFalseFalseFalse() {
		testSavePart(ISaveHandler.Save.CANCEL, false, false, false);
	}
	private void testSavePart_NoHandler(boolean beforeDirty,
			boolean throwException, boolean confirm) {
		MApplication application = ApplicationFactoryImpl.eINSTANCE
				.createApplication();
		MWindow window = BasicFactoryImpl.eINSTANCE.createWindow();
		application.getChildren().add(window);
		MPart saveablePart = BasicFactoryImpl.eINSTANCE.createPart();
		saveablePart.setDirty(beforeDirty);
		saveablePart
				.setContributionURI("platform:/plugin/org.eclipse.e4.ui.tests/org.eclipse.e4.ui.tests.application.ClientEditor");
		window.getChildren().add(saveablePart);
		initialize(applicationContext, application);
		getEngine().createGui(window);
		ClientEditor editor = (ClientEditor) saveablePart.getObject();
		editor.setThrowException(throwException);
		
		applicationContext.set(ISaveHandler.class.getName(), null);
		EPartService partService = (EPartService) window.getContext().get(