#disabled description is not accurate

API page: http://api.drupal.org/api/drupal/developer!topics!forms_api_reference.ht...

The documentation states that using #disabled would only have a cosmetic effect on UI by greying out corresponding field(s) but is not enforced at submit time if user achieve to post values via some DOM manipulation.

Excerpt :

Disables (greys out) a form input element. Note that disabling a form field doesn't necessarily prevent someone from submitting a value through DOM manipulation. It just tells the browser not to accept input.

Actually the code does prevent user submitted value from being taken in account for #disabled elements :

(from form.inc)

// Setting #disabled to TRUE results in user input being ignored, regardless
// of how the element is themed or whether JavaScript is used to change the
// control's attributes.

So, setting #disabled to a form element does disable the rendered item UI AND prevent values from beeing submitted.