[IxDA Discuss] select exact number widget?

[John Schrag]

Victor wrote:
> Conceptually, an option I'm considering is like selecting
> two apples from a pile of apples at the market, as you select
> them they are moved away from the group. So the shopper understands
> you can only pick two, the apples are moved into an area just
> big enough for two apples. This approach requires a way to
> unselect as well; with checkboxes that's already familiar.

If there must always be exactly two things selected, you could turn the
problem around.  Imagine the list of choices is visible, and by default
two of them are labelled somehow (say, with tags that say "1" and "2").
The UI would then allow the user to move the tags to any position on the
list (except over top of each other), rather than moving the list items
themselves.

An advantage of this approach is that it ensures that there are always
two items selected; you don't have invalid intermediate states, where
zero or one items have been selected.

There are all kinds of refinements you could make on such a design, of
course.

-john