Bug 7235 [Contributions] Need dispose() for action delegates
bundles/org.eclipse.jface/src/org/eclipse/jface/action/MenuManager.java
* Returns whether the menu control is created
 * and not disposed.
 * 
 * @return <code>true</code> if the control is created
 *	and not disposed, <code>false</code> otherwise
 */
private boolean menuExist() {
	return menu != null && !menu.isDisposed();
}
/* (non-Javadoc)
 * Method declared on IMenuManager.
 */
public void removeMenuListener(IMenuListener listener) {
	listeners.remove(listener);
}
/* (non-Javadoc)
 * Method declared on IMenuManager.
 */
public void setRemoveAllWhenShown(boolean removeAll) {
	this.removeAllWhenShown = removeAll;
}
/* (non-Javadoc)
 * Method declared on IContributionItem.
 */
public void setVisible(boolean visible) {
	this.visible = visible;
}
/**
 * Sets the overrides for this contribution manager
 *