Bug 176436 Charts Imported from Libraries do not update when libraries change
During a live presentation of BIRT at EclipseCon, we came across a rather embarassing issue. When charts are included in a library, and imported into a report design from a library, any changes to the library instance of the chart do not reflect in the report itself.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/DesignElementHandle.java
* @return an iterator over the elements that derive from this one. Each
	 *         item returned by the iterator's <code>getNext( )</code> method
	 *         is of type {@link DesignElementHandle}.
	 */
	public Iterator derivedIterator( )
	{
		return new DerivedElementIterator( module, this );
	}
	/**
	 * Returns an iterator over the clients of this element, e.g. other elements
	 * which reference this element.
	 * 
	 * @return an iterator over the clients of this element. Each item returned
	 *         by the iterator's <code>getNext( )</code> method is of type
	 *         {@link DesignElementHandle}. Nothing will be iterated over an
	 *         element that is not <code>ReferenceableElement</code>.
	 */
	public Iterator clientsIterator( )
	{
		return new ClientIterator( this );
	}
	/**
	 * Returns a array of valid choices for a property.
	 * 
	 * @param propName
	 *            the property name
	 * @return a array containing choices for the given property. Return
	 *         <code>null</code>, if this property has no choice.
	 */
	public IChoice[] getChoices( String propName )