Bug 317485 Minimized detached window reappears after switching perspectives
1. Detach the 'Outline' view. 2. Minimize it. 3. Switch perspectives. 4. Switch back. 5. An extra shell for the detached window is visible.
bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/LazyStackRenderer.java
private EventHandler lazyLoader = new EventHandler() {
		public void handleEvent(Event event) {
			Object element = event.getProperty(UIEvents.EventTags.ELEMENT);
			if (!(element instanceof MGenericStack<?>))
				return;
			MGenericStack<MUIElement> stack = (MGenericStack<MUIElement>) element;
			LazyStackRenderer lsr = (LazyStackRenderer) stack.getRenderer();
			if (lsr == null)
				return;
			
			MUIElement oldSel = (MUIElement) event
					.getProperty(UIEvents.EventTags.OLD_VALUE);
			if (oldSel != null) {
				List<MUIElement> goingHidden = new ArrayList<MUIElement>();