function ProgressBar(builder, options) {
            this.options = options || Object.create(null);
            objects_1.mixin(this.options, defaultOpts, false);
            this.toUnbind = [];
            this.workedVal = 0;
            this.progressBarBackground = this.options.progressBarBackground;
            this.create(builder);
        }
A progress bar with support for infinite or discrete progress.