var siteurl='http://www.showtribe.com/';
function CheckFieldLength(fn,wn,rn,mc) {
  var len = fn.value.length;
  if (len > (mc/2)) {
    fn.value = fn.value.substring(0,mc);
    len = fn.value.length;
  }

  //document.getElementById(wn).innerHTML = len;
  if (len > (mc/2) && len <= mc) {
  document.getElementById('imagesubmit').innerHTML="<img src=\"http://www.showtribe.com/images/btn_share_hide.jpg\"     name=\"imgshare\" />";
  document.getElementById(rn).innerHTML = '-' + (len - 140);
  }
  if (len <= (mc/2)){
  document.getElementById('imagesubmit').innerHTML="<img src=\"http://www.showtribe.com/images/btn_share.jpg\" onclick=\" saveTweet();\"  name=\"imgshare\" />";
  document.getElementById(rn).innerHTML =  (mc/2) - len;
  }
}