requestBlurScreen(id) {
    if (id != null) {
      if (!_.contains(this._blurScreenRequests, id)) {
        const numRequests = this._blurScreenRequests.length;
        this._blurScreenRequests.push(id);
        if (numRequests === 0 && this._blurScreenRequests.length === 1) {
          this.getEventBus().trigger(EVENTS.blur_screen_start, { type: EVENTS.blur_screen_start });
        }
      }
    } else {
      Logger.module('ENGINE').error('FX.requestBlurScreen -> requires id');
    }
  }
Request blur of entire screen.
@param {String|Number|Integer} id