Returns the current grouping for this widget.
        
        :return     [<str> group level, ..]

def currentGrouping( self ):
        """
        Returns the current grouping for this widget.
        
        :return     [<str> group level, ..]
        """
        groupBy = self.groupBy()
        if ( groupBy == XOrbBrowserWidget.GroupByAdvancedKey ):
            return self.advancedGrouping()
        else:
            table = self.tableType()
            if ( not table ):
                return []
            
            for column in table.schema().columns():
                if ( column.displayName() == groupBy ):
                    return [column.name()]
            
            return []