function goback() {
    history.go(-1);
}

function clearField(obj){
  obj.value='';
}

//preload images for main navigation

var imgNames = ['images/nav-main-tortenelem-h.gif', 
                'images/nav-main-tortenelem.gif', 
                'images/nav-main-kfkozpont-h.gif', 
                'images/nav-main-kfkozpont.gif', 
                'images/nav-main-partnereink-h.gif', 
                'images/nav-main-partnereink.gif', 
                'images/nav-main-referenciak-h.gif',
                'images/nav-main-referenciak.gif'];
var imgObjects = [];

for (var i = 0; i < imgNames.length; i++)
{
  imgObjects[i] = new Image();
  imgObjects[i].src = imgNames[i];
}

//rollovers

function mainOver(obj,i){
  obj.style.background = 'url(' + imgObjects[i].src + ') no-repeat';
}

function mainOut(obj,i){
  obj.style.background = 'url(' + imgObjects[i].src + ') no-repeat';
}

//bagcround position

function setBgPosition(obj,x,y){
    obj.style.backgroundPosition = x +'px ' + y + 'px';
}

//add remove class

function addClass(target, classValue)
{
  var pattern = new RegExp("(^| )" + classValue + "( |$)");

  if (!pattern.test(target.className))
  {
    if (target.className == "")
    {
      target.className = classValue;
    }
    else
    {
      target.className += " " + classValue;
    }
  }

  return true;
}

function removeClass(target, classValue)
{
  var removedClass = target.className;
  var pattern = new RegExp("(^| )" + classValue + "( |$)");

  removedClass = removedClass.replace(pattern, "$1");
  removedClass = removedClass.replace(/ $/, "");

  target.className = removedClass;

  return true;
}