[Taxonomy] empty taxonomy field not highlighted when required.

http://www.onehippo.org/library/concepts/plugins/taxonomy/required-taxonomy-field.html describes how to make a field required, and that the field gets highlighted when it's required but empty. The screenshot in that document does, however, not show the highlighting. I used the demo to try to get the highlighting going, but following the steps in the documentation, the taxonomy field would not be highlighted.

Reality and documentation should be brought into sync, and if reality is that there is highlighting (preferred), the screenshot in the documentation needs to be updated.