You can register to be notified whenever the
dropLocation property changes.
You would listen for this change and
do your own rendering of the drop location in a custom renderer
for the component or in the paintComponent method,
using the getDropLocation method.
Here is an example of listening for the dropLocation
property:
class Repainter extends PropertyChangeListener {
    public void propertyChange(PropertyChangeEvent pce) {
        repaintDropLocation(pce.getOldValue());
        repaintDropLocation(pce.getNewValue());
    }
}
comp.addPropertyChangeListener("dropLocation", newRepainter());
Here is an example of the paintComponent approach:
public void paintComponent(Graphics g) {
    super.paintComponent(g);
    DropLocation loc= getDropLocation();
    if (loc == null) {
        return;
    }
    renderPrettyIndicatorAt(loc);
}