Bug 319169 [UI] active parts in Detached windows prevent activating a part in the main window
Start with a fresh WS Detach the Outline view using DnD Now you can no longer activate any part in the main window (i.e. Package Explorer). The cause seems to be that the 'rootContainer' has become the DW's MTrimmedWindow rather than the DW's containing MPerspective. This causes the PartService's 'activate' to fail the 'isInContainer()' test...
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/application/EPartServiceTest.java
window.setSelectedElement(stack);
		MPart partA = BasicFactoryImpl.eINSTANCE.createPart();
		stack.getChildren().add(partA);
		stack.setSelectedElement(partA);
		
		initialize(applicationContext, application);
		
		getEngine().createGui(window);
		EPartService partService = (EPartService) window.getContext().get(
				EPartService.class.getName());
		partService.activate(partA);
		MPart partB = partService.showPart("partId", partState);
		
		assertNotNull("The part should have been rendered", partB.getContext());
	}
	public void testShowPart_Bug307747_CREATE() {
		testShowPart_Bug307747(PartState.CREATE);
	}
	public void testShowPart_Bug307747_VISIBLE() {
		testShowPart_Bug307747(PartState.VISIBLE);
	}
	public void testShowPart_Bug307747_ACTIVATE() {
		testShowPart_Bug307747(PartState.ACTIVATE);
	}
	private MApplication createApplication(String partId) {
		return createApplication(new String[] { partId });
	}
	private MApplication createApplication(String... partIds) {
		return createApplication(new String[][] { partIds });
	}