Bug 146481 Name is not necessary for extended element
Steps to reproduce: 1.New a label named "label" in library 2.New a report, extend lib.label Expected result: No name for the extended label Actual result: "label" is added as the name of label in report. It's not reasonable because "Restore Properties" is enabled even without properties change.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/GroupElementHandle.java
for ( Iterator iter = elements.iterator( ); iter.hasNext( ); )
		{
			DesignElementHandle elementHandle = (DesignElementHandle) iter
					.next( );
			Iterator propIter = elementHandle.getPropertyIterator( );
			while ( propIter.hasNext( ) )
			{
				PropertyHandle propertyHandle = (PropertyHandle) propIter
						.next( );
				String name = propertyHandle.getDefn( ).getName( );
				if ( IDesignElementModel.EXTENDS_PROP.equals( name ) )
					continue;
				
				if ( elementHandle.getElement( ).getLocalProperty(
						elementHandle.getModule( ), name ) != null )
					return true;
			}
		}
		return false;
	}
	/**
	 * Checks whether a property is read-only in the property sheet. The visible
	 * property is read-only in all <code>elements</code>.
	 * 
	 * @param propName
	 *            the property name
	 * @return <code>true</code> if it is read-only. Otherwise
	 *         <code>false</code>.
	 */
	abstract protected boolean isPropertyReadOnly( String propName );