Bug 322356 EPS's isPartVisible(MPart) method does not consider placeholders
SSIA
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/application/EPartServiceTest.java
window.setSelectedElement(stack);
		MPart partA = BasicFactoryImpl.eINSTANCE.createPart();
		stack.getChildren().add(partA);
		stack.setSelectedElement(partA);
		
		initialize(applicationContext, application);
		
		getEngine().createGui(window);
		EPartService partService = (EPartService) window.getContext().get(
				EPartService.class.getName());
		partService.activate(partA);
		MPart partB = partService.showPart("partId", partState);
		
		assertNotNull("The part should have been rendered", partB.getContext());
	}
	public void testShowPart_Bug307747_CREATE() {
		testShowPart_Bug307747(PartState.CREATE);
	}
	public void testShowPart_Bug307747_VISIBLE() {
		testShowPart_Bug307747(PartState.VISIBLE);
	}
	public void testShowPart_Bug307747_ACTIVATE() {
		testShowPart_Bug307747(PartState.ACTIVATE);
	}
	private MApplication createApplication(String partId) {
		return createApplication(new String[] { partId });
	}
	private MApplication createApplication(String... partIds) {
		return createApplication(new String[][] { partIds });
	}