[IxDA Discuss] select exact number widget?

[Livia Labate]

Victor Lombardi wrote:
> Has anyone seen effective UI widgets for selecting an exact number of
> choices greater than 1? Radio buttons do this for 1, but it seems we have
> no standard for "Select two and only two choices."

I suggest presenting all options (in a list or whatever works for the 
number of elements you have); when an option is selected, it's visually 
emphasized (i.e.: bold, color, etc).

Once the second option is selected, it is also highlighted and the 
rejected options are de-emphasized (color subdued or whatever form of 
visual contrast).

De-selecting any of the two choices would reveal the rest of the 
rejected options in regular format (standard emphasis), until the limit 
choice is reached again.

Having the choice selector be the choice itself (your apples) rather 
than a check box or a radio button associated with the choice probably 
removes the larger challenge of this not being a very standard 
interaction (multiple choice equal to 2) - check boxes and radio buttons 
already have an established model and expectations. This same model can 
work with any scenarios of selections 'up to n'.

I like this approach because it respects a very basic usability 
guideline allowing the user to "do and undo" - and without the sense of 
there being an error, just a change of heart. I also like it because it 
does not involve any error scenarios or messaging.

I imagine it would be an elegant solution - I can visualize it in Flash 
or just basic HTML/CSS.