The new quick form field uses a choice list to display a dropdown
component inside a form. Apart from que quick form code, the patch also
include a small improvement to the choicelist class to disable empty
values. This small patch is needed because the quickform field won't
allow empty values.
The choicelist output class is designed to represent a user choice in
several formats like a dropdown or subpanel. In general, other
components are free to render the choice in its own way. However, to
simplify the logic the choicelist now provide a default template to be
used in any div or panel.
Ferran Recio