Bug 142928 Item from library is changed to a report design item after revert to report item
Details: Item from library is changed to a report design item after revert to report item. Setp: 1.New a template. 2.Use a libary contain a label. 3.Drop the label from library explorer into layout. 4.Change the label to template item. 5.Revert the template item to report item. Actual result: The label is become a report item, but a item from library. Please see the attach image. Exception result: The lable is revert a item from library.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/DesignElementHandle.java
*            the name of the user property to remove
	 * @throws UserPropertyException
	 *             If the property is not found.
	 */
	public void dropUserPropertyDefn( String propName )
			throws UserPropertyException
	{
		DesignElement element = getElement( );
		UserPropertyCommand cmd = new UserPropertyCommand( module, element );
		cmd.dropUserProperty( propName );
	}
	/**
	 * Returns a handle to the element that this element extends.
	 * 
	 * @return the parent element. Returns <code>null</code> if this element
	 *         does not have a parent, or if the extends name does not resolve
	 *         to a valid element.
	 */
	public DesignElementHandle getExtends( )
	{
		DesignElement parent = getElement( ).getExtendsElement( );
		if ( parent == null )
			return null;
		return parent.getHandle( parent.getRoot( ) );
	}
	/**
	 * Sets this element to extend the given element.
	 * 
	 * @param parent
	 *            handle to the element that this element is to extend. If