jQuery.extend(DateInput.DEFAULT_OPTS, {
  month_names: ["Styczeń", "Luty", "Marzec", "Kwiecień", "Maj", "Czerwiec", "Lipiec", "Sierpień", "Wrzesień", "Październik", "Listopad", "Grudzień"],
  short_month_names: ["Sty", "Lut", "Mar", "Kwi", "Maj", "Cze", "Lip", "Sie", "Wrz", "Paź", "Lis", "Gru"],
  short_day_names: ["Nie", "Pon", "Wto", "Śro", "Czw", "Pią", "Sob"],
  
  stringToDate: function(string) {
    var matches;
    if (matches = string.match(/^(\d{4,4})-(\d{2,2})-(\d{2,2})$/)) {
      return new Date(matches[1], matches[2] - 1, matches[3]);
    } else {
      return null;
    };
  },

  dateToString: function(date) {
    var month = (date.getMonth() + 1).toString();
    var dom = date.getDate().toString();
    if (month.length == 1) month = "0" + month;
    if (dom.length == 1) dom = "0" + dom;	
    return this.short_day_names[date.getDay()] + ", " + dom + "-" + month + "-" + date.getFullYear();	
  }
});