sub level program option?

i noticed fairly early'ish after updating that sub-level windows couldn't be assigned a different icon anymore, i.e. msn messenger main contact window having a typical msn icon, and conversation windows with your contacts have something like a dialog bubble. i figured i'd just play ball and deal on that account if i had to, but i finally noticed it's not even limited to that close of a relation. now every folder that's open has the same icon and shares it with pictureviewer even. is this a mistake? an accident? i can't imagine this was intended.