Bug 329184 Detached view that is an activation target candidate can prevent perspective switching
1. Detach the 'Outline' view. 2. Window > Open Perspective > Debug 3. Window > Open Perspective > Java 4. The perspective switch doesn't actually happen. You see the 'Debug' perspective's content with an 'Outline' view detached. Closing the 'Outline' view in the 'Debug' perspective will workaround this problem.
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/application/EPartServiceTest.java
public void testSwitchPerspective01() {
		MApplication application = ApplicationFactoryImpl.eINSTANCE
				.createApplication();
		MWindow window = BasicFactoryImpl.eINSTANCE.createWindow();
		application.getChildren().add(window);
		application.setSelectedElement(window);
		MPerspectiveStack perspectiveStack = AdvancedFactoryImpl.eINSTANCE
				.createPerspectiveStack();
		window.getChildren().add(perspectiveStack);
		window.setSelectedElement(perspectiveStack);
		MPerspective perspectiveA = AdvancedFactoryImpl.eINSTANCE
				.createPerspective();
		perspectiveStack.getChildren().add(perspectiveA);
		perspectiveStack.setSelectedElement(perspectiveA);
		MPerspective perspectiveB = AdvancedFactoryImpl.eINSTANCE
				.createPerspective();
		perspectiveStack.getChildren().add(perspectiveB);
		initialize(applicationContext, application);
		getEngine().createGui(window);
		IEclipseContext windowContext = window.getContext();
		IEclipseContext perspectiveContextA = perspectiveA.getContext();
		assertEquals(perspectiveContextA, windowContext.getActiveChild());
		window.getContext().get(EPartService.class)
				.switchPerspective(perspectiveB);
		IEclipseContext perspectiveContextB = perspectiveB.getContext();
		assertEquals(perspectiveContextB, windowContext.getActiveChild());
	}
	public void testSwitchPerspective02() {
		MApplication application = ApplicationFactoryImpl.eINSTANCE
				.createApplication();