Bug 7235 [Contributions] Need dispose() for action delegates
bundles/org.eclipse.jface/src/org/eclipse/jface/action/IContributionItem.java
public boolean isVisible();
/**
 * Sets the parent manager of this item
 * 
 * @param parent the parent contribution manager
 * @since 2.0
 */
public void setParent(IContributionManager parent);
/**
 * Sets whether this contribution item is visibile within its manager.
 *
 * @param visible <code>true</code> if this item should be visible, and
 *  <code>false</code> otherwise
 */
public void setVisible(boolean visible);
/**
 * Updates any SWT controls cached by this contribution item with any
 * changes which have been made to this contribution item since the last update.
 * Called by contribution manager update methods.
 */
public void update();
/**
 * Updates any SWT controls cached by this contribution item with changes
 * for the the given property. 
 * 
 * @param String id the di of the changed property
 * @since 2.0
 */
public void update(String id);
}