Bug 232048 [Viewers] binary incompatibility (adding public fields) reported against jface.viewers
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/CellEditor.java
* Adds a property change listener to this cell editor. Has no effect if an
	 * identical property change listener is already registered.
	 *
	 * @param listener
	 *            a property change listener
	 */
	public void addPropertyChangeListener(IPropertyChangeListener listener) {
		propertyChangeListeners.add(listener);
	}
	/**
	 * Creates the control for this cell editor under the given parent control.
	 * <p>
	 * This framework method must be implemented by concrete subclasses.
	 * </p>
	 *
	 * @param parent
	 *            the parent control
	 * @return the new control, or <code>null</code> if this cell editor has
	 *         no control
	 */
	protected abstract Control createControl(Composite parent);
	/**
	 * Creates the control for this cell editor under the given parent control.
	 *
	 * @param parent
	 *            the parent control
	 * @since 2.1
	 */
	public void create(Composite parent) {
		Assert.isTrue(control == null);