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
perspectiveStack.getChildren().add(perspective);
		perspectiveStack.setSelectedElement(perspective);
		MPlaceholder placeholder = AdvancedFactoryImpl.eINSTANCE
				.createPlaceholder();
		placeholder.setRef(part);
		placeholder.setToBeRendered(false);
		perspective.getChildren().add(placeholder);
		
		initialize(applicationContext, application);
		
		getEngine().createGui(window);
		EPartService partService = (EPartService) window.getContext().get(
				EPartService.class.getName());
		partService.hidePart(part, force);
		assertEquals(force, !perspective.getChildren().contains(placeholder));
	}
	public void testHidePart_Bug325148_True() {
		testHidePart_Bug325148(true);
	}
	public void testHidePart_Bug325148_False() {
		testHidePart_Bug325148(false);
	}
	private void testHidePart_Bug325148_Unrendered(boolean force) {
		MApplication application = ApplicationFactoryImpl.eINSTANCE
				.createApplication();
		MPartDescriptor partDescriptor = org.eclipse.e4.ui.model.application.descriptor.basic.impl.BasicFactoryImpl.eINSTANCE
				.createPartDescriptor();
		partDescriptor.setElementId("partId");
		partDescriptor.setCategory("category");
		application.getDescriptors().add(partDescriptor);