Using a couple of widgets, (Long Description and FreeHTML) I noticed only the option [class seems to work. From the help on this issue from achillis it seems there is no ID attached to the objects so they can't be modified. See post http://forums.b2evolution.net/css-on-widgets. I suppose each time a widget is created it would need an increased number WidgID, or maybe the option for an ID could just be removed.