function GetXmlHttpObject() {
  var xmlHttp=null;
  try { // Firefox, Opera 8.0+, Safari
    xmlHttp=new XMLHttpRequest();
  }
  catch (e) { // Internet Explorer
    try {
      xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
    }
    catch (e) {
      xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
    }
  }
  return xmlHttp;
}

function ShowSubCategories(categoryId) {
	var action = (arguments[1]) ? arguments[1] : ""; 

  //alert("categoryId:" +  categoryId);
  if(document.getElementById('ul_' + categoryId).className == 'invisible') {
    xmlHttp=GetXmlHttpObject();
    if (xmlHttp == null) {
      alert ("Your browser does not support AJAX!");
      return;
    }
    var url = "/CategoryListShowSubCategories.php";
    url = url + "?cc=" + categoryId;
    url = url + "&a=" + action;
    url = url + "&sid=" + Math.random();
    xmlHttp.open('GET', url, false);
    xmlHttp.send(null);
    var response = xmlHttp.responseText.replace(/(?:(?:^|\n)\s+|\s+(?:$|\n))/g,"");
    document.getElementById('ul_' + categoryId).innerHTML = "";
    document.getElementById('ul_' + categoryId).innerHTML = response;
    document.getElementById('ul_' + categoryId).className = 'sub';
    document.getElementById('CategoryCtrl_' + categoryId).innerHTML = '<img src="/images/CategoryListCollapse.png" alt="zbaľ" />';
  }
  else {
    document.getElementById('ul_' + categoryId).className = 'invisible';
    document.getElementById('CategoryCtrl_' + categoryId).innerHTML = '<img src="/images/CategoryListExpand.png" alt="rozbaľ" />';
  }
}