Code example for PropertyChangeSupport

			INCOMINGS = "incomings", //$NON-NLS-1$
			OUTGOINGS = "outgoings", //$NON-NLS-1$
			LINESTYLE = "linestyle", //$NON-NLS-1$
			BOUNDS = "bounds"; //$NON-NLS-1$
	transient protected PropertyChangeSupport listeners = new PropertyChangeSupport(this);
	static final long serialVersionUID = 1;
	public void addPropertyChangeListener(PropertyChangeListener l) {
	protected void firePropertyChange(String prop, Object old, Object newValue) {
		listeners.firePropertyChange(prop, old, newValue);
	protected void fireStructureChange(String prop, Object child) {
		listeners.firePropertyChange(prop, null, child);
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