function getWindowHeight() {
  var mbody;
  if (document.documentElement && document.documentElement.clientHeight) {
    mbody = document.documentElement;
  } else if (document.body && document.body.clientHeight) {
    mbody=document.body;
  }
  return mbody.clientHeight + mbody.scrollTop;
}

function setFooter() {
  if (document.getElementById) {
    var windowHeight = getWindowHeight();
    var footerElement = document.getElementById('footer');
    var footerHeight  = footerElement.offsetHeight;
    
    if (footerElement.offsetTop < windowHeight)
      footerElement.style.top = (windowHeight-footerHeight)+'px';

    //var webetui = document.getElementById('webetui');
    //webetui.style.top = (windowHeight-footerHeight - 20)+'px';
  }
}

onresize=setFooter;
onscroll=setFooter;
onload= setFooter;