Nice idea!
Wouldn't this also fire on every other event (when removing lines) ? I think an event check should be added to be on the safe side:
$("#field_container_{{ admin.uniqId }}_images").livequery(function(
event) {
if('event' == '_some_event_name_') image_preview();
});
Another solution could be to add the
sonata-collection-add class name to the button, but I don't know how to do that elegantly.