Returns the list of column names for this table widget's columns.
        
        :return     [<str>, ..]

def columns( self ):
        """
        Returns the list of column names for this table widget's columns.
        
        :return     [<str>, ..]
        """
        output = []
        for c in range(self.columnCount()):
            hitem  = self.horizontalHeaderItem(c)
            text = nativestring(hitem.text())
            if ( not text ):
                text = nativestring(hitem.toolTip())
            output.append(text)
        return output