Bug 327765 EPartService will hide a part of another perspective
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/application/EPartServiceTest.java
partService.activate(partB);
		partService.switchPerspective(perspectiveB);
		assertEquals(
				"partB is in both perspectives, active part should have been preserved",
				partB, partService.getActivePart());
		partService.hidePart(partB);
		assertEquals("Hiding partB should have caused partA to be activated",
				partA, partService.getActivePart());
		partService.switchPerspective(perspectiveA);
		assertEquals(
				"partB is the only part in perspectiveA, thus, it should be the active part",
				partB, partService.getActivePart());
		partService.switchPerspective(perspectiveB);
		assertEquals(
				"partA should be the only part that's being shown in perspectiveB, thus, it should be the active part",
				partA, partService.getActivePart());
	}
	/**
	 * Test to ensure that switching perspectives doesn't cause a hidden shared
	 * part to be displayed again.
	 */
	public void testHidePart_ActivationHistory16C() {
		MApplication application = ApplicationFactoryImpl.eINSTANCE
				.createApplication();
		MWindow window = BasicFactoryImpl.eINSTANCE.createWindow();
		application.getChildren().add(window);
		application.setSelectedElement(window);
		MPart partA = BasicFactoryImpl.eINSTANCE.createPart();
		window.getSharedElements().add(partA);
		MPart partB = BasicFactoryImpl.eINSTANCE.createPart();