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
EPartService.class.getName());
		EPartService partServiceB = (EPartService) windowB.getContext().get(
				EPartService.class.getName());
		partServiceA.bringToTop(partBackB);
		assertEquals(partStackA.getSelectedElement(), partFrontA);
		assertEquals(partStackB.getSelectedElement(), partFrontB);
		partServiceB.bringToTop(partBackA);
		assertEquals(partStackA.getSelectedElement(), partFrontA);
		assertEquals(partStackB.getSelectedElement(), partFrontB);
		partServiceA.bringToTop(partBackA);
		assertEquals(partStackA.getSelectedElement(), partBackA);
		assertEquals(partStackB.getSelectedElement(), partFrontB);
		partServiceB.bringToTop(partBackB);
		assertEquals(partStackA.getSelectedElement(), partBackA);
		assertEquals(partStackB.getSelectedElement(), partBackB);
	}
	public void testBringToTop_PartInAnotherWindow_myService() {
		MApplication application = createApplication(new String[] {
				"partFrontA", "partBackA" }, new String[] { "partFrontB",
				"partBackB" });
		MWindow windowA = application.getChildren().get(0);
		MPartStack partStackA = (MPartStack) windowA.getChildren().get(0);
		MPart partFrontA = (MPart) partStackA.getChildren().get(0);
		MPart partBackA = (MPart) partStackA.getChildren().get(1);
		partStackA.setSelectedElement(partFrontA);
		MWindow windowB = application.getChildren().get(1);
		MPartStack partStackB = (MPartStack) windowB.getChildren().get(0);
		MPart partFrontB = (MPart) partStackB.getChildren().get(0);
		MPart partBackB = (MPart) partStackB.getChildren().get(1);
		partStackB.setSelectedElement(partFrontB);