IMHO the handling of transitions is not very intuitive and might confuse new users, since they have to be enabled by double clicking on it first.
Why isn't it possible to select a transition by a single click?
Also the transitions connot be dragged out of the transition view since they are all disabled by default, but I think most user prefer this way to add transitions.
Could this be changed?
Or is there a special reason why it is designed this way?