Bug 123406 Add geLocaltStringProperty in GroupElementHandle and GroupPropertyHandle
Please refer to 123405. GUI need a way to get the local setting of given property because current getStringPropery method will return inherited value if there are no local value.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/GroupPropertyHandle.java
* 
	 * @return list of the reference element value.
	 */
	public List getReferenceableElementList( )
	{
		if ( propDefn.getTypeCode( ) != PropertyType.ELEMENT_REF_TYPE )
			return Collections.EMPTY_LIST;
		ElementDefn elementDefn = (ElementDefn) propDefn.getTargetElementType( );
		assert elementDefn != null;
		List elementList = null;
		assert handle.getModuleHandle() != null;
		if ( ReportDesignConstants.DATA_SET_ELEMENT.equals( elementDefn
				.getName( ) ) )
		{
			elementList = handle.getModuleHandle( ).getAllDataSets( );
		}
		else if ( ReportDesignConstants.DATA_SOURCE_ELEMENT.equals( elementDefn
				.getName( ) ) )
		{
			elementList = handle.getModuleHandle( ).getAllDataSources( );
		}
		else if ( ReportDesignConstants.STYLE_ELEMENT.equals( elementDefn
				.getName( ) ) )
		{
			elementList = handle.getModuleHandle( ).getAllStyles( );
		}
		else if ( ReportDesignConstants.THEME_ITEM.equals( elementDefn
				.getName( ) ) )
		{
			elementList = handle.getModuleHandle( ).getAllThemes( );