Bug 176450 Support link to CSS Feature(Model Part)
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/command/PropertyCommand.java
public void clearProperty( String propName ) throws SemanticException
	{
		setProperty( propName, null );
	}
	/**
	 * Sets the value of the member of a structure.
	 * 
	 * @param ref
	 *            reference to the member to set
	 * @param value
	 *            new value of the member
	 * @throws SemanticException
	 *             if the value is not valid
	 */
	public void setMember( MemberRef ref, Object value )
			throws SemanticException
	{
		PropertyDefn memberDefn = ref.getMemberDefn( );
		PropertyDefn propDefn = ref.getPropDefn( );
		assert propDefn != null;
		assertExtendedElement( module, element, propDefn );
		assert memberDefn != null;
		value = memberDefn.validateValue( module, value );
		
		
		if ( memberDefn.getTypeCode( ) == IPropertyType.NAME_TYPE
				|| memberDefn.getTypeCode( ) == IPropertyType.MEMBER_KEY_TYPE )
			checkItemName( ref, (String) value );
		if ( value instanceof ElementRefValue
				&& memberDefn.getTypeCode( ) == IPropertyType.ELEMENT_REF_TYPE )