Update: problem fixed by adding an "Announcer" to the "double click" event, i.e.:
morWidget onAnnouncement: FTStrongSelectionChanged send: #doubleClick: to: self. Where "morWidget" is the morphic object representing a list of pictures, "self" is the "MorphicPictureListAdapter", which creates the "morWidget" object. The method "doubleClick:" contains the actions to be performed when the event is triggered. Note that, in the "FTAnnouncement" hierachy, the "double click" event is represented by the class "FTStrongSelectionChanged", which I found a little tricky. Bye, Matteo