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
new String[] { "partInWindow1" },
				new String[] { "partInWindow2" });
		MWindow window1 = application.getChildren().get(0);
		MWindow window2 = application.getChildren().get(1);
		getEngine().createGui(window1);
		getEngine().createGui(window2);
		EPartService partService = (EPartService) window1.getContext().get(
				EPartService.class.getName());
		MPart part = partService.findPart("partInWindow2");
		assertNull(part);
		part = partService.findPart("partInWindow1");
		assertNotNull(part);
		MPartStack partStack = (MPartStack) window1.getChildren().get(0);
		assertEquals(partStack.getChildren().get(0), part);
		partService = (EPartService) window2.getContext().get(
				EPartService.class.getName());
		part = partService.findPart("partInWindow1");
		assertNull(part);
		part = partService.findPart("partInWindow2");
		assertNotNull(part);
		partStack = (MPartStack) window2.getChildren().get(0);
		assertEquals(partStack.getChildren().get(0), part);
	}
	public void testBringToTop_PartOnTop() {
		MApplication application = createApplication("partFront", "partBack");
		MWindow window = application.getChildren().get(0);
		MPartStack partStack = (MPartStack) window.getChildren().get(0);
		MPart partFront = (MPart) partStack.getChildren().get(0);
		partStack.setSelectedElement(partFront);
		getEngine().createGui(window);