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
* context.
	 * 
	 * @param slotId
	 *            the slot id
	 * @param element
	 *            the element to insert
	 * @throws NameException
	 *             if name duplicate occurs
	 * @throws ContentException
	 *             the slot cannot contain the given element.
	 */
	private void checkContainmentContext( int slotId, DesignElement content )
			throws NameException, ContentException
	{
		List errors = element.checkContainmentContext( module, slotId, content );
		if ( !errors.isEmpty( ) )
		{
			SemanticException e = (SemanticException) errors.get( 0 );
			assert e instanceof NameException || e instanceof ContentException;
			if ( e instanceof NameException )
				throw (NameException) e;
			if ( e instanceof ContentException )
				throw (ContentException) e;
		}
	}
	/**
	 * Adds the element name and names of nested element in it to name spaces.
	 * 
	 * @param content
	 *            the content to add