numOfTabs		    = 4;
headerTabsIntervalTime 	    = 5000;
currentHeaderTab 	    = 1;
headerTabsInterval	    = null;

function headerTabs(id){
  for(var e = 1; e <= 4; e++){
  var imgName;
  var newImgName;
    if(id==e){
      document.getElementById(e).style.display="block";
          imgName=document.getElementById(e+10).src;
          newImgName=imgName.replace("off", "on");
          document.getElementById(e+10).src=newImgName; 	  
    }else{
      if(document.getElementById(e)){
        document.getElementById(e).style.display="none";
                imgName=document.getElementById(e+10).src;
            newImgName=imgName.replace("on", "off");
            document.getElementById(e+10).src=newImgName;
      }
    }
  }
}

function headerTabsClicked(id)
{
  clearHeaderTabsInterval();
  headerTabs(id);
}

function rotateHeaderTabs()
{
  if (currentHeaderTab == numOfTabs)
  {
    currentHeaderTab = 1;
  }
  else
  {
    currentHeaderTab += 1;
  }
  headerTabs(currentHeaderTab);
}

function clearHeaderTabsInterval()
{
    window.clearInterval(headerTabsInterval);
}

function setHeaderTabsInterval()
{

  headerTabsInterval = window.setInterval(function(){rotateHeaderTabs()}, headerTabsIntervalTime);
}

window.onload = function(){setHeaderTabsInterval()};