function set_iframe_height (iframeName) {
  var iframeWin = window.frames[iframeName];
  var iframeEl = document.getElementById? document.getElementById(iframeName): document.all? document.all[iframeName]: null;
  if ( iframeEl && iframeWin ) {
    iframeEl.style.height = "auto"; // helps resize (for some) if new doc shorter than previous  
    var docHt = get_doc_height(iframeWin.document);
    // need to add to height to be sure it will all show
    if (docHt) iframeEl.style.height = docHt + 30 + "px";
  }
}