After seeing this thread, a thought occurred. Instead of (as well as ?) the rather small and fiddly drop-down list in chests where it is easy to accidentally pass something to the wrong person, why not utilise the existing list of party members? Double-clicking an item in the chest or hitting "Loot All" can work the same way they've always done, but you could pass items to other people by clicking on it once in the chest and then clicking on the person in the party list (or hitting the corresponding F-key).