How to freeze selection in jQuery UI widget - Selectables?

How to freeze selection in jQuery UI widget - Selectables?

Hi there,

I've implemented the selectable plugin as shown in the tutorial ( http://jqueryui.com/demos/selectable/).

I want that only preselected items should be selected and rest of the items should not get deselected/selected through mouse click/keyboard. Its like I want to freeze my selection programatically. How to achieve this?
Edit: Additionally I tried the disabled option, but that doesn't seem to work.

$( ".selector" ).selectable( "disable" );

Cheers,
S