ForEach visualization should show null values as 'null' and empty string as "" in the collapsed entry
sshot @ http://i.imgur.com/xiotN.png
Having null be represented as 'null' (perhaps in italics font or whatever) would allow the user to differentiate.
Secondary but less important would be to have empty string show up as "" in the collapsed entry, but since other strings don't have surrounding quotes in the collapsed entry, I could see that as less desirable (although IMHO having the quotes in the collapsed entry is better since it helps make it explicit that it's a string)
Customer support service by UserEcho