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);

// map hover effects
var def_map_img  = "";
var def_img_path = "../img/";

function mapHover(grp, id) {
  def_map_img = $("#" + grp + "_img").attr("src");
  $("#" + grp + "_img").attr("src", def_img_path + grp + "_" + id + def_img_ext);
}
function mapOut(grp) {
  $("#" + grp + "_img").attr("src", def_map_img);
}