Sets the join operator type for this entry widget to the given value.
        
        :param      joiner | <QueryCompound.Op>

def setJoiner(self, joiner):
        """
        Sets the join operator type for this entry widget to the given value.
        
        :param      joiner | <QueryCompound.Op>
        """
        text = QueryCompound.Op[joiner].upper()
        
        if self._first:
            if self._last:
                self.uiJoinSBTN.setCurrentAction(None)
            else:
                act = self.uiJoinSBTN.findAction(text)
                self.uiJoinSBTN.setCurrentAction(act)
        else:
            self.uiJoinSBTN.actions()[0].setText(text)