Code example for PropertyChangeSupport

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			TARGETS = "targets", SOURCES = "sources",
			ACTIVITY_STATUS = "activity_status", COLUMN = "column",
			BENDPOINT = "bendpoint", ACTIVE_COLUMN = "bg_color",
			NUMBER_ID = "number_id", DELAY = "delay";
 
	protected PropertyChangeSupport listeners = new PropertyChangeSupport(this);
 
	public void addPropertyChangeListener(PropertyChangeListener pcl) {
		listeners.addPropertyChangeListener(pcl);
	} 
 
	protected void firePropertyChange(String propName, Object old,
			Object newValue) {
		listeners.firePropertyChange(propName, old, newValue);
	} 
 
	public PropertyChangeSupport getListeners() {
		return listeners;
	} 
 
	public void removePropertyChangeListener(PropertyChangeListener pcl) {