function btnOn() 
  {
    var srcString = this.src
    srcString = srcString.replace(/.gif/,'_over.gif')
    this.src = srcString
  }
function btnOff() 
  {
    var srcString = this.src
    srcString = srcString.replace(/_over.gif/,'.gif')
    this.src = srcString
  }
  
function checkLinks()
  {
    var maincontent = document.getElementById('maincontent');
    if (maincontent == null) return
    var contentLx = maincontent.getElementsByTagName('A')
    for (var cl = 1; cl < contentLx.length; cl++)
    {
      if (contentLx[cl].className.match(/popup/)) {contentLx[cl].onclick = function(){newwindow(this.href); return false}}
    }
  }
checkLinks()