function toggleDisplay(objectID) {
  var object = document.getElementById(objectID);
  state = object.style.display;
  if( state == 'block' ) object.style.display = 'none';
  else object.style.display = 'block';
  return;
}

function setDisplay(objectID, state) {
  var object = document.getElementById(objectID);
  if(!state) var state = 'block'; 
  object.style.display = state;
  return;
}


function swapDisplay(a,b) {
/* shows a, hides b */
  setDisplay(a,'block');
  setDisplay(b,'none');
  return;
}

function changeClass(objectID, newClass) {
  var object = document.getElementById(objectID);
  object.className = newClass;
}

function swapLanguage(a,b) {
   swapDisplay(a,b);
   changeClass(a+'link', 'linkoff');
   changeClass(b+'link', 'linkon')

}