I have not found any reference to this in the sources
and reading the map definitions I believe this has not
been implemented yet.
Since Slashem introduces 'drow' objects and drows get
an added bonus when using them it might be worth adding
to the code some kind of check to special levels that
might have some kind of sunlight that might either
destroy drow objects.
A new FLAG could be added to levels to indicate if they
are open to the sky, this flag could be checked when
entering (or walking through) and affect drow objects
(destroying them directly or through a progressive
corroding process). Sunlight levels could also have
negative effects for drow player characters.