Take the 2-minute tour ×  I have a field for which the user may
select multiple responses, and is likely to be implemented as a
drop-down with checkboxes. The user can select one, two, or many
from the list of options. We're even providing a "All options"
option to speed things along.  The field has one last
requirement though, and that is that the user must select at
least one option. They can select and de-select each option
independently, but they must leave at least one selected.
Normally with a form we can also do field-validation, but in
this case the values selected are dynamically linked into a
chart thing and so we're looking for a UI which effectively
forces the constraint.  Any suggestions?  share|improve this
question Why force a constraint? Couldn't you just show an empty
graph when nothing was selected? –  Marjan Venema Oct 17 '11 at
8:28  4 Answers 4  up vote 3 down vote accepted  A pattern for
this problem exists as such:    1. by default the 'all options'
checkbox is checked   2. once a user