Best 20 lines of Swing KeyboardFocusManager code I've ever written ;)

KeyboardFocusManager.getCurrentKeyboardFocusManager().addPropertyChangeListener("focusOwner", new PropertyChangeListener() {
   Color FOCUS_COLOR = Color.CYAN;
   Component last;
   Color background = null;
   public void propertyChange(PropertyChangeEvent evt) {
      Component current = (Component)evt.getOldValue();
      Component future = (Component)evt.getNewValue();

         if(current==last && current != null) {

         last = future;
         if(last!=null) {
            background = last.getBackground();

....and voila! you get EVERY component that can ever get focus hightligted with your favorite color!
This is great for debugging focus traversal problems - and it actually also looks cool (at least if you find a better color ,)

If I also just could do this for the ToolTipManager then my gui-debugging would ROCK ;)

p.s. No patent is currently pending on similar code - at least none that i'm aware of (wink wink Ward ;)