anchor.diff:    static void setCursor(Thing thing, String value) {
       assert(thing != null);
       if(value == null) {
  -      _cursorProperty.clear(thing);
  +      cursorProperty.clear(thing);
       } else {
  -      _cursorProperty.set(thing, value);
  +      cursorProperty.set(thing, value);
       }
     }
   
     static String getCursor(Thing thing) {
       assert(thing != null);
  -    return _cursorProperty.get(thing);
  +    return cursorProperty.get(thing);
     }
   
     static void setClickable(Thing thing, bool value) {
  
positive.code:         }
        }
      }
      _updateCursor(cursor);
    }
  
    void _mouseOut(MouseEvent e) {
      _updateMouseLocation(null);
      _mouseOutEvent.fireEvent(_stage, EventArgs.empty);
      _updateCursor(null);
    }
  
    void _mouseUp(MouseEvent e) {
  
negative.code:     }
    }
  
    void _updateStageCursor(String cursor) {
      cursorProperty.set(_stage, cursor);
    }
  
    List<Thing> _updateMouseLocation(Coordinate value) {
  