Bug 251257 [Contributions] IAction.setImageDescriptor() javadoc needs to note "image vs. checked" platform discrepancy
bundles/org.eclipse.jface/src/org/eclipse/jface/action/IAction.java
* property change events are reported when its value changes.
     * </p>
     *
     * @return <code>true</code> if enabled, and
     *   <code>false</code> if disabled
     * @see #ENABLED
     */
    public boolean isEnabled();
    /**
	 * Returns whether this action is handled. In the default case, this is
	 * always <code>true</code>. However, if the action delegates some of its
	 * behaviour to some other object, then this method should answer whether
	 * such an object is currently available.
	 * 
	 * @return <code>true</code> if all of the action's behaviour is
	 *         available; <code>false</code> otherwise.
	 * @since 3.1
	 */
	public boolean isHandled();
    /**
     * Removes the given listener from this action.
     * Has no effect if an identical listener is not registered.
     *
     * @param listener a property change listener
     */
    public void removePropertyChangeListener(IPropertyChangeListener listener);
    /**
     * Runs this action.
     * Each action implementation must define the steps needed to carry out this action.
     * The default implementation of this method in <code>Action</code>