MAX(ROW(...)) - feature request

Hello. Since release 8.2 row comparisons work well - thanks! It would be nice if MIN and MAX aggregate functions could
operateon row values, so I could write in SQL: 

SELECT MIN(ROW(a, b, c, d)) FROM table

to find extreme value of ordered set of columns. It should not be hard to implement, please.

I'm looking forward to release 8.4 which will introduce window functions.