var Xteam = {
    /**
     * Calculate the difference between 2 arrays
     * @param {array} before
     * @param {array} after
     * @return {hash}
     */
    diff: function(before, after) {
        before = before || [];
        after = after || [];
        var result = {added: [], removed: []};

        // check for added items (in after, not in before)
        for (var i=0, len=after.length; i<len; i++) {
            if ($.inArray(after[i], before) == -1) {
                result.added.push(after[i]);
            }
        }

        // check for removed items (in before, not in after)
        for (i=0, len=before.length; i<len; i++) {
            if ($.inArray(before[i], after) == -1) {
                result.removed.push(before[i]);
            }
        }

        return result;
    }
};

var Screens = {

};

var Registry = {

};