If we use the green halo to cue "hey, try to check your answer here", then it doesn't make sense to show the green halo when the collection area already contains an answer. You can't answer the same challenge twice. I'd say if a collection area already has an answer, don't show the green halo on hover.
If we use the green halo to cue "hey, try to check your answer here", then it doesn't make sense to show the green halo when the collection area already contains an answer. You can't answer the same challenge twice. I'd say if a collection area already has an answer, don't show the green halo on hover.
For phetsims/tasks/issues/860.