Bug 154828 Item from library contant user properties can't delete
Details: Item from library contant user properties can't delete Step: 1.New a library. 2.Add a label and add a user properites. 3.Public the library. 4.New a report design and use the library 5.Drop the label from library explorer into layout. 6.Try to delete it. Actual result: The label from library contant user properties can't be delete. Exception reuslt: The label can be delete.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/command/ContentCommand.java
*/
	public void add( DesignElement content, int slotID, int newPos )
			throws ContentException, NameException
	{
		assert newPos >= 0 || newPos == -1;
		doAdd( content, slotID, newPos );
	}
	/**
	 * Adds a new element into a container. Virtually all elements must reside
	 * in a container. Containers are identified by a container ID. The
	 * application creates the element object, then adds it to the container
	 * here. The undo of this operation effectively deletes the element.
	 * 
	 * @param content
	 *            the element to add
	 * @param slotID
	 *            the slot in which to add the component
	 * @throws ContentException
	 *             if the content cannot be added into this container.
	 * @throws NameException
	 *             if the name of the content exists in name space.
	 */
	public void add( DesignElement content, int slotID )
			throws ContentException, NameException
	{
		doAdd( content, slotID, -1 );
	}
	/**
	 * Adds a new element into a container. Virtually all elements must reside
	 * in a container. (The term "container" here is generic, it is not the same