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
EPartService.class.getName());
		assertNull(partService.createSharedPart("partId", window));
	}
	public void testCreateSharedPart_ForceFalse() {
		MApplication application = createApplication(1, new String[1][0]);
		MPartDescriptor partDescriptor = org.eclipse.e4.ui.model.application.descriptor.basic.impl.BasicFactoryImpl.eINSTANCE
				.createPartDescriptor();
		partDescriptor.setElementId("partId");
		application.getDescriptors().add(partDescriptor);
		MWindow window = application.getChildren().get(0);
		getEngine().createGui(window);
		EPartService partService = (EPartService) window.getContext().get(
				EPartService.class.getName());
		MPlaceholder placeholderA = partService.createSharedPart("partId",
				window, false);
		MPlaceholder placeholderB = partService.createSharedPart("partId",
				window, false);
		assertEquals(1, window.getSharedElements().size());
		MPart part = (MPart) window.getSharedElements().get(0);
		assertEquals(part, placeholderA.getRef());
		assertEquals(part, placeholderB.getRef());
	}
	public void testCreateSharedPart_ForceTrue() {
		MApplication application = createApplication(1, new String[1][0]);
		MPartDescriptor partDescriptor = org.eclipse.e4.ui.model.application.descriptor.basic.impl.BasicFactoryImpl.eINSTANCE
				.createPartDescriptor();
		partDescriptor.setElementId("partId");
		application.getDescriptors().add(partDescriptor);
		MWindow window = application.getChildren().get(0);
		getEngine().createGui(window);