var viewportWidth = 0;
  var viewportHeight = 0;

  function getHeight(obj) {
    if (document.getElementById(obj)) return document.getElementById(obj).offsetHeight;
    else return 0;
  }

  function setHeight(obj,value) {
    if (document.getElementById(obj)) document.getElementById(obj).style.height = value + 'px';
  }

  function getScreenWidth() {
    isNetscape = (navigator.appName == "Netscape");
    available = (isNetscape) ? window.innerWidth : document.body.clientWidth;
    return available;
  }
  
  function getScreenHeight() {
    isNetscape = (navigator.appName == "Netscape");
    available = (isNetscape) ? window.innerHeight : document.body.clientHeight;
    return available;
  }


  function setHeights() {
    viewportWidth = getScreenWidth() - 10;
    viewportHeight = getScreenHeight() - 120;
    h = Math.max(getHeight('left'),getHeight('middle'),getHeight('right'));
    setHeight('left',h + 36);
    setHeight('middle',h);
    setHeight('right',h);
  }

  function isEmail(emailStr) {
    var checkTLD=1;
    var knownDomsPat=/^(com|net|org|edu|int|mil|gov|arpa|biz|aero|name|coop|info|pro|museum)$/;
    var emailPat=/^(.+)@(.+)$/;
    var specialChars="\\(\\)><@,;:\\\\\\\"\\.\\[\\]";
    var validChars="\[^\\s" + specialChars + "\]";
    var quotedUser="(\"[^\"]*\")";
    var ipDomainPat=/^\[(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\]$/;
    var atom=validChars + '+';
    var word="(" + atom + "|" + quotedUser + ")";
    var userPat=new RegExp("^" + word + "(\\." + word + ")*$");
    var domainPat=new RegExp("^" + atom + "(\\." + atom +")*$");
    var matchArray=emailStr.match(emailPat);
    if (matchArray==null) return false;
    var user=matchArray[1];
    var domain=matchArray[2];
    for (i=0; i<user.length; i++) {
      if (user.charCodeAt(i)>127) return false;
    }
    for (i=0; i<domain.length; i++) {
      if (domain.charCodeAt(i)>127) return false;
    }
    if (user.match(userPat)==null) return false;
    var IPArray=domain.match(ipDomainPat);
    if (IPArray!=null) {
      for (var i=1;i<=4;i++) {
        if (IPArray[i]>255) return false;
      }
      return true;
    }
    var atomPat=new RegExp("^" + atom + "$");
    var domArr=domain.split(".");
    var len=domArr.length;
    for (i=0;i<len;i++) {
      if (domArr[i].search(atomPat)==-1) return false;
      if (checkTLD && domArr[domArr.length-1].length!=2 && domArr[domArr.length-1].search(knownDomsPat)==-1) return false;
      if (len<2) return false;
      return true;
    }
  }