function addLoadEvent(func) {
  var oldonload = window.onload;
  if (typeof window.onload != 'function') {
    window.onload = func;
  } else {
    window.onload = function() {
      oldonload();
      func();
    }
  }
}

function externalLinks() {
   if (!document.getElementsByTagName) return;
   var anchors = document.getElementsByTagName("a");
   for (var i=0; i<anchors.length; i++) {
      var anchor = anchors[i];
      if (anchor.getAttribute("href") && anchor.getAttribute("rel") == "external")
         anchor.target = "_blank";
      if (anchor.getAttribute("href") && anchor.getAttribute("rel") == "top")
         anchor.target = "_top";
   }
}

// define onload events
addLoadEvent(externalLinks);

/*
function setRandomHeadImage() {
  var i=1;
  var n=8;
  var ranNum= Math.floor(Math.random()*n)+i;
  var cami='images/';

  var thehead = document.getElementById('header');
  if (thehead) thehead.style.backgroundImage = 'url('+cami+'hdr_bg_'+ranNum+'.jpg)';
}

addLoadEvent(setRandomHeadImage);
*/