Multi-valued checkbox: No way to get all values checked

If a field in the view has multiple values (a checkbox with multiple items, for example), the field is not presented by views_customfield. So for example, a checkbox with multiple values named "my_checkbox" will not even show up in the Views-customfield $data element unless "Do not group" is selected for the field in queston. if the field is set to "Group Multiple Values" or to "First only" or "Last only". If you set to "Do not group multiple values", then the field is presented with the single choice, but of course the record is repeated, which is not appropriate for many uses.

Attached is a tarball containing an exported content type, an exported view, and a screenshot of a sample record.

Also attached is a screenshot of view output, showing the $data element (with no member for the checkbox).

This is Drupal 5.13, Views 5.x-1.6

Thanks for the excellent work on this.