Sections on the form are broken if the field of type HTML contains <form> tags in the content and the field is made readonly via an ACL.
1) Create 3 sections on the form.
2) On the first section create a field of type HTML and add the following content to the source.
3) For the other sections add few fields.
4) Create an ACL to make HTML the field read only.
When accessed the form as user who has read only access, the second and third sections on the form will be broken (when clicked on the section tab, nothing happens)
Forms tags are not supported on the field type of HTML
Remove the <form></form> tags from the source of the HTML field.