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
assertTrue(partService.isPartVisible(partBackB));
		partService.bringToTop(partBackA);
		assertEquals(partBackA, partService.getActivePart());
		assertFalse(partService.isPartVisible(partFrontA));
		assertTrue(partService.isPartVisible(partBackA));
		assertFalse(partService.isPartVisible(partFrontB));
		assertTrue(partService.isPartVisible(partBackB));
	}
	public void testBringToTop_Unrendered() {
		MApplication application = createApplication("partFront", "partBack");
		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);
		partBack.setToBeRendered(false);
		partStack.setSelectedElement(partFront);
		window.setSelectedElement(partStack);
		application.setSelectedElement(window);
		initialize(applicationContext, application);
		getEngine().createGui(window);
		assertFalse(partBack.isToBeRendered());
		EPartService partService = (EPartService) window.getContext().get(
				EPartService.class.getName());
		partService.bringToTop(partBack);
		assertTrue("Bringing a part to the top should cause it to be rendered",
				partBack.isToBeRendered());
	}
	public void testGetParts_Empty() {
		MApplication application = createApplication(1, new String[1][0]);
		MWindow window = application.getChildren().get(0);