Bug 307747 EPartService doesn't render new parts
1. Have a part in a stack, it is the selected part. 2. Show another part in that stack using PartState.CREATE or PartState.VISIBLE. 3. The part should've been rendered. It is not.
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/application/EPartServiceTest.java
assertFalse(partServiceB.isPartVisible(partFrontA));
		assertFalse(partServiceB.isPartVisible(partBackA));
		assertTrue(partServiceB.isPartVisible(partFrontB));
		assertFalse(partServiceB.isPartVisible(partBackB));
		partServiceB.activate(partBackB);
		assertEquals(partBackB, partServiceB.getActivePart());
		assertFalse(partServiceB.isPartVisible(partFrontA));
		assertFalse(partServiceB.isPartVisible(partBackA));
		assertFalse(partServiceB.isPartVisible(partFrontB));
		assertTrue(partServiceB.isPartVisible(partBackB));
	}
	public void testActivate_partService_SelectedElement() {
		MApplication application = createApplication(new String[] {
				"partFrontA", "partBackA" }, new String[] { "partFrontB",
				"partBackB" });
		MWindow windowA = application.getChildren().get(0);
		MPartStack partStackA = (MPartStack) windowA.getChildren().get(0);
		MPart partFrontA = partStackA.getChildren().get(0);
		MPart partBackA = partStackA.getChildren().get(1);
		partStackA.setSelectedElement(partFrontA);
		MWindow windowB = application.getChildren().get(1);
		MPartStack partStackB = (MPartStack) windowB.getChildren().get(0);
		MPart partFrontB = partStackB.getChildren().get(0);
		MPart partBackB = partStackB.getChildren().get(1);
		partStackB.setSelectedElement(partFrontB);
		getEngine().createGui(windowA);
		getEngine().createGui(windowB);
		EPartService partServiceA = (EPartService) partFrontA.getContext().get(
				EPartService.class.getName());
		EPartService partServiceB = (EPartService) partFrontB.getContext().get(