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
*/
    public ImageDescriptor getDisabledImageDescriptor();
    /**
     * Returns a help listener for this action. 
     *
     * @return a help listener for this action
     */
    public HelpListener getHelpListener();
    /**
     * Returns the hover image for this action as an image descriptor.
     * <p>
     * Hover images will be used on platforms that support changing the image
     * when the user hovers over the item. This method is associated with 
     * the <code>IMAGE</code> property;
     * property change events are reported when its value changes.
     * </p>
     *
     * @return the image, or <code>null</code> if this action has no image
     * @see #IMAGE
     */
    public ImageDescriptor getHoverImageDescriptor();
    /**
     * Returns a unique identifier for this action, or <code>null</code> if it has
     * none.
     *
     * @return the action id, or <code>null</code> if none
     */
    public String getId();
    /**
     * Returns the image for this action as an image descriptor.