//Available tabs
var tabs = new Array("for", "about", "courses", "research");

function change(oldClass, newClass) 
{
   var tagged=document.getElementsByTagName('a');
   for(var i = 0 ; i < tagged.length ; i++)
   {
      if (tagged[i].className==oldClass)
      {
         tagged[i].className=newClass;
      }
   }
}

function displayTab(tab)
{
   for (i=0; i < 4; i++)
   {
     document.getElementById("group" + i).style.display = "none";
   }
   
   if (tab != -1)
   {
      document.getElementById("group" + tab).style.display = "block";
   }
}

function switchTab(tabNum)
{
   for (i=0; i<tabs.length; i++)
   {
      change(tabs[i] + "on", tabs[i]); 
   }
   
   if (tabNum != -1)
   {
      change(tabs[tabNum], tabs[tabNum] + "on");       
   }
   
   displayTab(tabNum);
}