The newest version of web2py has added some + and - clickable links to form elements so that it is possible to remove the element. However, if there is only one element and one clicks the "-", the form disappears and there's no way to get the form element back without refreshing the page.
I'll post an image so that you can see what it looks like. I think this is a bug with the newest version because my code hasn't changed at all. There was only a "+" before... --
<<attachment: with_form_elt.png>>
<<attachment: without_form_elt.png>>
