function hideFormElement(elementname, formstring) {
  window.document.forms[formstring].elements[elementname].style.visibility='hidden';
}

function selectChange(parameterstring, formstring) {

  var elem;
  
  form = window.document.forms[formstring];

  elem = document.createElement("input");
  elem.type = 'hidden';
  elem.name = parameterstring;
  elem.value = 'XXX';
  form.appendChild(elem);
  form.submit();

}

function disableButton(btnName, formstring) {
  selectChange(btnName, formstring);
  window.document.forms[formstring].elements[btnName].disabled=true;
}