Improve Group functionality
Overall, I really like Justinmind (though I have only been using it for about one week), but I do find that Groups can be frustrating to work with in this program. Grouping elements together in a logical and consistent manner is a key element in UX design, so this is not a minor issue. I find that I am constantly having to group and ungroup elements and assign the same event to multiple objects.
I would suggest the following enhancements.
1. Give developers a method of selecting an item within a group (Adobe uses a different selector, which might be the best solution).
2. Either enable developers to set an event for a group, or enable developers to select multiple objects that events act upon (or best of all both). I do notice that it is possible to multi-select screens in the "Link to" section of the Interaction screen, but it is not possible to select multiple objects in the other sections. This seems like an unnecessary inconsistency.