Bug 214706 Script UID doens't work for Chart
Use chart "onRender" property handle and call ModuleUtil.getScriptUID(), it generates the id. But later use this id to get back the PropertyHandle or Script content, it fails.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/PropertyHandle.java
return getContents( ).size( );
	}
	/**
	 * Moves the position of a content element within the slot.
	 * 
	 * @param content
	 *            handle to the content to move
	 * @param toPosn
	 *            the new position
	 * @throws ContentException
	 *             if the content is not in the slot, or if the to position is
	 *             not valid.
	 */
	public void shift( DesignElementHandle content, int toPosn )
			throws ContentException
	{
		if ( content == null )
			return;
		ContentCommand cmd = new ContentCommand( getModule( ),
				new ContainerContext( getElement( ), propDefn.getName( ) ) );
		cmd.movePosition( content.getElement( ), toPosn );
	}
	/**
	 * Moves a content element into a slot in another container element.
	 * 
	 * @param content
	 *            a handle to the element to move
	 * @param newContainer
	 *            a handle to the new container element
	 * @param propName