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
MWindow window = BasicFactoryImpl.eINSTANCE.createWindow();
		application.getChildren().add(window);
		application.setSelectedElement(window);
		MPartDescriptor partDescriptor = org.eclipse.e4.ui.model.application.descriptor.basic.impl.BasicFactoryImpl.eINSTANCE
				.createPartDescriptor();
		partDescriptor.setAllowMultiple(multipleAllowed);
		partDescriptor.setElementId("partId");
		application.getDescriptors().add(partDescriptor);
		initialize(applicationContext, application);
		getEngine().createGui(window);
		EPartService partService = (EPartService) window.getContext().get(
				EPartService.class.getName());
		MPart createdPart = partService.createPart("partId");
		MPart shownPart = partService.showPart(createdPart, partState);
		assertNotNull(shownPart);
		assertEquals(createdPart, shownPart);
	}
	public void testShowPart_Part_MultipleNonexistent_TrueACTIVATE() {
		testShowPart_Part_MultipleNonexistent(true, PartState.ACTIVATE);
	}
	public void testShowPart_Part_MultipleNonexistent_FalseACTIVATE() {
		testShowPart_Part_MultipleNonexistent(false, PartState.ACTIVATE);
	}
	public void testShowPart_Part_MultipleNonexistent_TrueVISIBLE() {
		testShowPart_Part_MultipleNonexistent(true, PartState.VISIBLE);
	}
	public void testShowPart_Part_MultipleNonexistent_FalseVISIBLE() {
		testShowPart_Part_MultipleNonexistent(false, PartState.VISIBLE);
	}
	public void testShowPart_Part_MultipleNonexistent_TrueCREATE() {