How can I set default (global) options for helpers?

I need to fix the problem with body element and the css overflow attribute discussed in this post: When a fancybox 2 is activated, a scrollbar flashes on the parent page causing the content to shift left and then back

Using the helper option helpers: {overlay: {locked: false}} fixes my problem, but I need a solution to set this option for all Fancybox calls, this way I do not need to spend this setting on each call.

I tried with different forms, but doesn't works:

$.fancybox.open([{
    helpers: {
        overlay: {
            locked: false
        }
    }
}]);

$.extend($.fn.fancybox.helpers, {
    overlay: {
        locked: false
    }
});

$.fn.fancybox.defaults.overlay.locked = false;

I do not want to change the css component, because currently use the same via Bower.