var oldonload = window.onload;

window.onload = function() {
  var links = document.getElementById('nav').getElementsByTagName('LI');

  for ( var i = 0; i < links.length; i++ ) {
    var link = links[i];
  
    if ( i > 0 ) {
      link.previousLi = links[i-1];
    }
  
    link.onmouseover = hoverBorder;
    link.onmouseout = normalBorder;
  }

  if ( null != oldonload ) {
    oldonload();
  }
}

function hoverBorder( li ) {
  this.style.backgroundImage = "url('images/navrollover.png')";
  var links = this.getElementsByTagName('A');
  if ( null != links[0] && links[0].style.backgroundImage != 'none') {
    links[0].style.backgroundImage = "url('images/navrighthoverborder.png')";
  }

  if ( null == this.previousLi ) {
    return;
  }

  links = this.previousLi.getElementsByTagName('A');
  if ( null != links[0] ) {
    links[0].style.backgroundImage = "url('images/navhoverborder.png')";
  }
}

function normalBorder() {
  this.style.backgroundImage = "url('images/navbg.png')";
  var links = this.getElementsByTagName('A');
  if ( null != links[0] && links[0].style.backgroundImage != 'none') {
    links[0].style.backgroundImage = "url('images/navrightborder.png')";
  }

  if ( null == this.previousLi ) {
    return;
  }

  var links = this.previousLi.getElementsByTagName('A');
  if ( null != links[0] ) {
    links[0].style.backgroundImage =  "url('images/navrightborder.png')";
  }
}