As detailed in the specification for this non-standard feature, you can use none | text | all | element
So in your case:
function UNDO_AttIvAselecT(){
$('*').attr('unselectable','off')
.css({'-moz-user-select':'-moz-all',
'-moz-user-select':'all',
'-o-user-select':'all',
'-khtml-user-select':'all',
'-webkit-user-select':'all',
'-ms-user-select':'all',
'user-select':'all'
}).unbind('selectstart');
};