1 add validation like all the other widgets have. Where you can make the frontend show a warning, for instance when you have set validation to required, but the user entered no value.
2 add favorite-list on top. For instance in a countrylist, show the current country on top. Or on a list of artists, show the top 3 most popular artists on top.
Two very good suggestions, but especially adding the validation (as already there for other even very basic widgets) is a must imho.
Great idea！