public Dockable combine(CombinerSource source, CombinerTarget target) { if (target instanceof DisplayerTarget) { return ((DisplayerTarget) target).execute(source); } else { DockStation parent = source.getParent(); PlaceholderMap placeholders = source.getPlaceholders(); StackDockStation stack = new StackDockStation(parent.getTheme()); stack.setController(parent.getController()); if (placeholders != null) { stack.setPlaceholders(placeholders); } stack.drop(source.getOld()); stack.drop(source.getNew()); return stack; } }