Friends.CheckboxLabel = new function() {
    this.prefix = 'CheckboxLabel-';
    this.createFromTag = function(element, params) {
        var checkbox = y5.Dom.getDescendant(element, '*', this.prefix + 'Checkbox');
        var text = y5.Dom.getDescendant(element, '*', this.prefix + 'Text');

        function check(e) {
            checkbox.checked = (y5.Strings.trim(text.value).length > 0);
        }
        y5.Events.create('keyup', check, text, true);
    };
}

y5.require(['Dom', 'Events', 'Strings'], function() {y5.loaded('{Friends}.CheckboxLabel')});