Doesn't initialize on Safari 4 when using els.mooeditable()

I've seen this behavior before. One way to fix this is by replacing:

Element.implement({
    mooEditable: function(options){
        return this.get('mooeditable', options);
    }
});

With:

Array.implement({
    mooEditable: function(options){
        return this.get('mooeditable', options);
    }
});

Do you think this is more of a MooTools bug?