Wrap single checkbox for boolean fields in fieldset

[thomasmassmann]

For better accessibility checkbox fields should be wrapped in a fieldset with a legend. The current implementation (https://github.com/plone/plone.app.z3cform/blob/master/plone/app/z3cform/templates/singlecheckboxbool_input.pt) wraps the checkbox in a div

Current implementation for the plone.versioning behavior (Plone 6, german):

The label for the field is the checkbox label (so the answer). This can be confusing for people, as the logical form pattern (label -> field) is broken.

An example is shown in Adam Silver’s book “Form Design Patterns”:

He uses a “question” -> “answer” pattern. This requires an additional setting for the widget in Plone, since the field only has one title and description. The title should be used for the label, and an additional checkbox title can be defined at the widget. If this one is not available, the title would be used a second time. An automatically created text for the answer as fallback if the checkbox title is not available is not recommended, as this can lead to unexpected wordings and confusing labels.

Example for the plone.versioning behavior (Plone 6, german) with a custom checkbox title: