Of HIG, Apple, and User-Centric Design

[Keith Martin]

>>>  A checkbox I can't uncheck is a surprise.
>>>[snip]


>But there is a difference whether the checkbox is enabled or not. A disabled
>checkbox is inactive, so it is perfectly normal that it can't be unchecked.
>However, the same is not true if that checkbox is enabled. Once it is enabled,
>one should be able to toggle its state.


Absolutely - this is a simple matter of having a choice which only 
applies if other conditions are in a particular state. The 
alternative would be to hide the checkbox completely unless the state 
called for it, but this isn't quite as 'open' an approach to UI 
design - and isn't necessarily as kind and helpful to the user.

k